Question 1: The skin's outermost layer is called the?

• endodermis
• epidermis (Correct answer)
• dermis
• hypodermis

Correct answer: epidermis

The epidermis is the outermost protective layer of the skin. It acts as a crucial barrier against water loss, pathogens, and environmental damage. This layer is primarily composed of keratinocytes and is responsible for producing melanin, which gives skin its color and protects against UV radiation.

Question 2: Which mite is responsible for scabies infestation?

• Sarcoptes scabiei var. hominis (Correct answer)
• Cheyletiella species
• Demodex folliculorum
• Dermanyssus gallinae

Correct answer: Sarcoptes scabiei var. hominis

Scabies is caused by the human itch mite Sarcoptes scabiei var. hominis, which burrows into the stratum corneum causing intense pruritus, especially at night.

Question 3: Which layer of the epidermis contains the highest concentration of melanocytes?

• Stratum basale (Correct answer)
• Stratum spinosum
• Stratum corneum
• Stratum granulosum

Correct answer: Stratum basale

Melanocytes reside primarily in the stratum basale (basal layer), where they transfer melanin to surrounding keratinocytes.

Question 4: What condition cause a scaly dermatitis to afflict areas of the skin that receive oil gland supply?

• seborrheic dermatitis (Correct answer)
• contact dermatitis
• eczema
• chronic dermatitis

Correct answer: seborrheic dermatitis

Seborrheic dermatitis is a common inflammatory skin condition characterized by scaly patches, redness, and often greasy skin. It specifically affects areas of the body rich in sebaceous (oil) glands, such as the scalp, face (around the nose, eyebrows), and chest. This condition is frequently associated with the overgrowth of a yeast called Malassezia, which thrives in oily environments.

Question 5: Kaposi sarcoma is associated with which herpesvirus, and which patient population is classically affected in epidemic KS?

• HHV-6; elderly Mediterranean men
• EBV; organ transplant recipients
• CMV; immunosuppressed patients
• HHV-8 (KSHV); patients with advanced HIV/AIDS (Correct answer)

Correct answer: HHV-8 (KSHV); patients with advanced HIV/AIDS

Human herpesvirus 8 (Kaposi sarcoma-associated herpesvirus) causes all forms of KS; epidemic KS affecting HIV-positive patients with AIDS was the most prevalent form during the AIDS epidemic.

Question 6: What is the term for excessive facial or body hair, especially in women?

• hirsutism (Correct answer)
• atrichia
• albinism
• alopecia

Correct answer: hirsutism

Hirsutism is a medical condition characterized by excessive growth of coarse, dark hair in a male-like pattern (e.g., on the face, chest, back) in women. It is typically caused by an excess of androgens (male hormones) or increased sensitivity of hair follicles to androgens. This differs from general hypertrichosis, which is excessive hair growth anywhere on the body.

Question 7: Which histological feature best characterizes Kaposi sarcoma and distinguishes it from other vascular tumors?

• Glomeruloid vascular structures within dermal nodules
• Cavernous dilated vascular channels lined by flat endothelium
• Epithelioid endothelial cells with hobnail morphology
• Slit-like vascular spaces with spindle cells and extravasated erythrocytes (Correct answer)

Correct answer: Slit-like vascular spaces with spindle cells and extravasated erythrocytes

Kaposi sarcoma shows slit-like irregular vascular spaces lined by spindle cells with extravasated red blood cells and hemosiderin deposition, reflecting its HHV-8-driven spindle cell proliferation.

Question 8: What is the purpose of patch testing in dermatology?

• To identify specific allergens causing allergic contact dermatitis (Correct answer)
• To confirm atopic dermatitis diagnosis
• To diagnose irritant contact dermatitis
• To detect immediate IgE-mediated hypersensitivity reactions

Correct answer: To identify specific allergens causing allergic contact dermatitis

Patch testing (epicutaneous testing) identifies specific causative allergens in type IV delayed hypersensitivity reactions responsible for allergic contact dermatitis.

Question 9: Which topical therapy is first-line treatment for molluscum contagiosum in immunocompetent children?

• Podophyllotoxin
• Watchful waiting or cantharidin application (Correct answer)
• Cidofovir cream
• Imiquimod 5% cream

Correct answer: Watchful waiting or cantharidin application

Molluscum contagiosum in immunocompetent children typically self-resolves; if treatment is desired, cantharidin (blister beetle extract) or watchful waiting are preferred approaches.

Question 10: Ash-leaf macules (hypopigmented macules), shagreen patches, and angiofibromas are cutaneous markers of which genodermatosis?

• McCune-Albright syndrome
• LEOPARD syndrome
• Tuberous sclerosis complex (Correct answer)
• Neurofibromatosis type 2

Correct answer: Tuberous sclerosis complex

Tuberous sclerosis complex presents with characteristic skin findings including ash-leaf macules (first sign), angiofibromas on the face, shagreen patches on the back, and periungual fibromas.

Question 11: What is the name of the embryological process by which melanocytes migrate from the neural crest to the epidermis?

• Neural crest cell migration (Correct answer)
• Dermal condensation
• Epidermal stratification
• Gastrulation

Correct answer: Neural crest cell migration

Melanocytes originate from neural crest cells that migrate during embryogenesis into the epidermis, dermis, and other tissues.

Question 12: The Auspitz sign, elicited by removing a psoriatic scale and seeing pinpoint bleeding, reflects what underlying histological feature?

• Dilated tortuous capillaries in elongated dermal papillae (Correct answer)
• Acanthosis of the epidermis
• Parakeratosis of the stratum corneum
• Dermal neutrophilic infiltrate

Correct answer: Dilated tortuous capillaries in elongated dermal papillae

Auspitz sign results from the very thin suprapapillary plate in psoriasis; removing scale exposes the engorged capillary tips, causing punctate bleeding.

Question 13: Pautrier microabscesses on skin biopsy are characteristic of which condition?

• Folliculitis decalvans
• Mycosis fungoides (Correct answer)
• Atopic dermatitis
• Psoriasis

Correct answer: Mycosis fungoides

Pautrier microabscesses are intraepidermal collections of atypical T lymphocytes (cerebriform nuclei) that are pathognomonic of mycosis fungoides (cutaneous T-cell lymphoma).

Question 14: What is the mechanism of action of cryotherapy in treating actinic keratoses?

• Selective thermolysis of pigmented cells
• Thermal denatura­tion of keratin proteins
• Chemical destruction of the stratum corneum
• Rapid freezing causes intracellular ice crystal formation and cell destruction (Correct answer)

Correct answer: Rapid freezing causes intracellular ice crystal formation and cell destruction

Cryotherapy destroys abnormal cells through rapid freezing with liquid nitrogen, causing intracellular ice crystal formation, membrane disruption, and subsequent cell death.

Question 15: 'Naked granulomas' (non-caseating granulomas with sparse surrounding lymphocytes) in skin biopsies are characteristic of which systemic condition?

• Sarcoidosis (Correct answer)
• Crohn's disease with cutaneous involvement
• Rheumatoid nodule
• Granuloma annulare

Correct answer: Sarcoidosis

Sarcoidosis produces 'naked' non-caseating epithelioid granulomas with minimal surrounding lymphocytic infiltrate, often with Langhans giant cells and inclusion bodies.

Question 16: Which vitamin, when severely deficient, causes pellagra with its classic triad of dermatitis, diarrhea, and dementia?

• Riboflavin (B2)
• Thiamine (B1)
• Pyridoxine (B6)
• Niacin (B3) (Correct answer)

Correct answer: Niacin (B3)

Pellagra results from niacin (vitamin B3) or tryptophan deficiency; the skin shows a photosensitive dermatitis in sun-exposed areas called casal necklace.

Question 17: What is the indication of pemphigus foliceus?

• Any age
• Elderly animals
• Young to middle age adults (Correct answer)
• Very young puppies

Correct answer: Young to middle age adults

Pemphigus foliaceus is an autoimmune skin disease that can affect various age groups, but it is most commonly diagnosed in young to middle-aged adult animals. It causes characteristic crusting and erosions, particularly on the face and ears.

Question 18: The white, half-moon-shaped region at the end of a fingernail is referred to as the?

• stratum
• cuticle
• lunula (Correct answer)
• basal layer

Correct answer: lunula

The lunula is the visible, white, half-moon-shaped area at the base of the fingernail or toenail. It is the visible part of the nail matrix, where new nail cells are produced. Its white appearance is due to the thickness of the nail matrix obscuring the blood vessels underneath.

Question 19: What is the recommended first-line topical treatment for localized superficial basal cell carcinoma?

• Diclofenac gel
• Tretinoin cream
• Imiquimod 5% cream (Correct answer)
• 5-fluorouracil cream

Correct answer: Imiquimod 5% cream

Imiquimod 5% cream is FDA-approved for superficial BCC and works as an immune response modifier stimulating innate and adaptive immunity against tumor cells.

Question 20: Which of the following is a high-risk feature of SCC that significantly increases metastatic potential?

• Presence on trunk
• Lesion arising de novo rather than from actinic keratosis
• Age <50 at diagnosis
• Tumor diameter >2 cm, depth >2 mm, perineural invasion, or immunosuppression (Correct answer)

Correct answer: Tumor diameter >2 cm, depth >2 mm, perineural invasion, or immunosuppression

High-risk SCC features include large size (>2 cm), deep invasion (>2 mm), poor differentiation, perineural or lymphovascular invasion, location on ear/lip, and patient immunosuppression.

Question 21: Flame figures in the dermis are classically associated with which dermatological condition?

• Granuloma annulare
• Wells syndrome (eosinophilic cellulitis) (Correct answer)
• Erythema nodosum
• Dermatitis herpetiformis

Correct answer: Wells syndrome (eosinophilic cellulitis)

Flame figures are eosinophilic granular deposits coating collagen fibers, characteristic of Wells syndrome (eosinophilic cellulitis), a recurrent eosinophilic dermatosis.

Question 22: Which of the following treatments for acne would be recommended?

• Accu-Check
• Actonel
• Accutane (Correct answer)
• Actiq

Correct answer: Accutane

Accutane (isotretinoin) is a powerful prescription medication commonly recommended by dermatologists for severe, recalcitrant nodular acne that has not responded to other treatments. It works by significantly reducing the size and activity of sebaceous glands, thereby decreasing oil production and preventing clogged pores. The other options are not treatments for acne.

Question 23: Sentinel lymph node biopsy is recommended for melanomas with Breslow thickness greater than which measurement?

• 1.5 mm
• 0.8 mm (or 0.8–1.0 mm with high-risk features) (Correct answer)
• 0.5 mm
• 2.0 mm

Correct answer: 0.8 mm (or 0.8–1.0 mm with high-risk features)

Current NCCN guidelines recommend sentinel lymph node biopsy for melanomas >0.8 mm in Breslow thickness, or for thinner melanomas with ulceration or high mitotic rate.

Question 24: Livedo reticularis presenting with systemic thrombosis and recurrent pregnancy loss suggests which underlying condition?

• Antiphospholipid syndrome (Correct answer)
• Livedoid vasculopathy
• Polyarteritis nodosa
• Cryoglobulinemia

Correct answer: Antiphospholipid syndrome

The combination of livedo reticularis, arterial or venous thrombosis, and recurrent pregnancy loss is the classic triad of antiphospholipid antibody syndrome.

Question 25: A child presents with thick, hyperkeratotic plaques on the elbows, knees, and scalp with nail pitting. Which condition is most likely?

• Tinea corporis
• Childhood psoriasis (Correct answer)
• Pityriasis rubra pilaris
• Atopic dermatitis

Correct answer: Childhood psoriasis

Psoriasis in children presents similarly to adults with thick scaly plaques on extensor surfaces and scalp, and nail changes (pitting, onycholysis) are common associated findings.

Question 26: Which topical retinoid is considered the gold standard for treating photodamage and acne?

• Tretinoin (all-trans retinoic acid) (Correct answer)
• Adapalene
• Tazarotene
• Retinol

Correct answer: Tretinoin (all-trans retinoic acid)

Tretinoin is the prototypical topical retinoid with the strongest evidence base for treating acne, photodamage, and fine wrinkles by modulating keratinocyte differentiation and stimulating collagen.

Question 27: BRAF V600E mutation is found in approximately what percentage of cutaneous melanomas?

• 10–15% of cutaneous melanomas
• 80–90% of cutaneous melanomas
• 5% of cutaneous melanomas
• 50–60% of cutaneous melanomas (Correct answer)

Correct answer: 50–60% of cutaneous melanomas

BRAF V600E mutations are present in approximately 50–60% of cutaneous melanomas, making BRAF/MEK inhibitor combination therapy (e.g., dabrafenib/trametinib) applicable to a large proportion of patients.

Question 28: Dupilumab (Dupixent) works by blocking the receptor for which cytokines in atopic dermatitis?

• IL-12 and IL-23
• IL-17A and IL-17F
• TNF-alpha and IL-1
• IL-4 and IL-13 (Correct answer)

Correct answer: IL-4 and IL-13

Dupilumab is a monoclonal antibody that blocks the IL-4Rα subunit shared by IL-4 and IL-13 receptors, inhibiting the Th2 inflammatory cascade central to atopic dermatitis.

Question 29: Acantholysis, the disruption of cell-to-cell adhesion between keratinocytes, is a hallmark histological finding in which condition?

• Dermatitis herpetiformis
• Pemphigus vulgaris (Correct answer)
• Epidermolysis bullosa
• Bullous pemphigoid

Correct answer: Pemphigus vulgaris

Pemphigus vulgaris features intraepidermal acantholysis due to IgG autoantibodies against desmoglein 3, causing suprabasal blisters with 'tombstone' basal cells.

Question 30: A neonate develops a widespread vesiculopustular eruption within the first 2 weeks of life. Tzanck smear shows multinucleated giant cells. What is the diagnosis?

• Neonatal candidiasis
• Neonatal herpes simplex (Correct answer)
• Erythema toxicum neonatorum
• Transient neonatal pustular melanosis

Correct answer: Neonatal herpes simplex

Neonatal HSV presents with vesiculopustular eruption in the first weeks of life; Tzanck smear showing multinucleated giant cells confirms herpetic etiology.

Question 31: Which skin-associated lymphoma is the most common primary cutaneous T-cell lymphoma and presents with patches, plaques, and tumors?

• Sézary syndrome
• Mycosis fungoides (Correct answer)
• Subcutaneous panniculitis-like T-cell lymphoma
• Primary cutaneous anaplastic large cell lymphoma

Correct answer: Mycosis fungoides

Mycosis fungoides is the most common primary cutaneous T-cell lymphoma, progressing from eczematous patches to plaques to tumors.

Question 32: Which skin finding is pathognomonic for Lyme disease?

• Vesiculobullous eruption following dermatome
• Petechiae and purpura on lower extremities
• Migratory salmon-colored plaques
• Erythema migrans — expanding annular erythema at tick bite site (Correct answer)

Correct answer: Erythema migrans — expanding annular erythema at tick bite site

Erythema migrans, the expanding bull's-eye or ring-shaped rash at the site of Borrelia burgdorferi-infected tick bite, is pathognomonic for early Lyme disease.

Question 33: Which electrosurgical technique uses alternating current to destroy tissue while controlling hemostasis?

• Iontophoresis
• Electrolysis
• Electrodesiccation and curettage (ED&C) (Correct answer)
• Radiofrequency ablation

Correct answer: Electrodesiccation and curettage (ED&C)

Electrodesiccation and curettage uses high-frequency alternating current to dehydrate and destroy superficial tumor tissue, followed by physical removal with a curette.

Question 34: Which gene is most commonly mutated in patients with familial melanoma?

• KIT
• CDKN2A (Correct answer)
• BRAF
• NRAS

Correct answer: CDKN2A

CDKN2A (encoding p16/INK4A) is the most commonly mutated gene in familial melanoma, significantly increasing lifetime risk.

Question 35: What is the recommended treatment for head lice (Pediculosis capitis) when permethrin 1% has failed?

• Higher concentration permethrin
• Lindane shampoo
• Ketoconazole shampoo
• Oral ivermectin or topical spinosad/benzyl alcohol (Correct answer)

Correct answer: Oral ivermectin or topical spinosad/benzyl alcohol

Resistance to permethrin is widespread; second-line options include oral ivermectin, topical spinosad (Natroba), or benzyl alcohol (Ulesfia), which work through different mechanisms.

Question 36: What is another word for itching?

• keratosis
• petechiae
• dermatitis
• pruritus (Correct answer)

Correct answer: pruritus

Pruritus is the medical term for itching, which is an unpleasant sensation that provokes the desire to scratch. It can be a symptom of various skin conditions, systemic diseases, allergic reactions, or even neurological disorders. Understanding the cause of pruritus is essential for effective treatment.

Question 37: The 'ABCDE' criteria for melanoma evaluation stands for asymmetry, border, color, diameter, and what fifth feature added later?

• Erythema
• Erosion
• Evolving (Correct answer)
• Elevation

Correct answer: Evolving

The 'E' in ABCDE was later defined as 'evolving,' meaning any change in size, shape, color, or new symptom over time warrants evaluation.

Question 38: What is excessive scaling?

• Dandruff
• Epidermal Collarette
• Gross
• Seborrhea (Correct answer)

Correct answer: Seborrhea

Seborrhea is a common skin condition characterized by excessive scaling, flaking, and sometimes greasiness of the skin. It results from an overproduction of sebum and/or abnormal keratinization, leading to visible flakes often referred to as dandruff.

Question 39: Which vitamin deficiency causes pellagra, characterized by dermatitis, diarrhea, and dementia?

• Vitamin B3 (niacin) (Correct answer)
• Vitamin B12 (cobalamin)
• Vitamin B1 (thiamine)
• Vitamin C (ascorbic acid)

Correct answer: Vitamin B3 (niacin)

Pellagra results from niacin (vitamin B3) deficiency and classically presents with the '3 Ds': dermatitis, diarrhea, and dementia.

Question 40: What is the Breslow depth, and why is it the most important prognostic factor in primary melanoma?

• Depth of surgical excision needed
• Tumor thickness measured in mm from the granular layer to deepest tumor cell; predicts metastatic risk and survival (Correct answer)
• Clark level of dermal invasion
• Distance from epidermis to nearest lymph node

Correct answer: Tumor thickness measured in mm from the granular layer to deepest tumor cell; predicts metastatic risk and survival

Breslow depth is the vertical tumor thickness in millimeters measured by pathology, directly correlating with 5-year survival — thicker melanomas have greater access to lymphatics and blood vessels for metastasis.

Question 41: A virus-induced epidermal growth is referred to as a?

• impetigo
• verruca (Correct answer)
• nevus
• melanoma

Correct answer: verruca

A verruca, commonly known as a wart, is a small, rough growth on the skin or mucous membrane caused by a viral infection, specifically by the human papillomavirus (HPV). These growths are benign and can appear anywhere on the body, varying in size and shape depending on the type of HPV and location.

Question 42: A port-wine stain (nevus flammeus) on the face in a V1 trigeminal distribution should prompt evaluation for which syndrome?

• Sturge-Weber syndrome (Correct answer)
• Klippel-Trenaunay syndrome
• Beckwith-Wiedemann syndrome
• PHACE syndrome

Correct answer: Sturge-Weber syndrome

Port-wine stains in the V1 (ophthalmic) distribution of the trigeminal nerve are associated with Sturge-Weber syndrome, which includes ipsilateral leptomeningeal angioma, glaucoma, and seizures.

Question 43: What are moles that have the potential to turn into malignant melanoma?

• verrucae
• intraderma nevi
• giant nevi
• dysplastic nevi (Correct answer)

Correct answer: dysplastic nevi

Dysplastic nevi are atypical moles that have irregular borders, varied color, and are often larger than common moles. While most dysplastic nevi do not become melanoma, they are considered precursors to malignant melanoma and indicate an increased risk for developing this serious skin cancer. Regular monitoring by a dermatologist is crucial for individuals with these moles.

Question 44: Atopy can be treated. True or False?

• False (Correct answer)
• True

Correct answer: False

Atopy, or atopic dermatitis, is a chronic, inherited allergic skin condition. While its symptoms can be managed with various treatments like medications, immunotherapy, and environmental control, there is currently no known cure for the underlying condition itself.

Question 45: What is the mechanism of action of terbinafine (Lamisil) in treating onychomycosis?

• Disrupts the cell wall beta-glucan synthesis
• Inhibits lanosterol 14α-demethylase
• Inhibits squalene epoxidase, blocking ergosterol synthesis and causing toxic squalene accumulation (Correct answer)
• Binds to fungal tubulin inhibiting mitosis

Correct answer: Inhibits squalene epoxidase, blocking ergosterol synthesis and causing toxic squalene accumulation

Terbinafine inhibits squalene epoxidase, an earlier step in ergosterol synthesis, causing dual toxicity — ergosterol depletion and accumulation of toxic squalene within the fungal cell.

Question 46: Which skin condition in pregnancy presents with intensely pruritic urticarial papules and plaques in the striae of the abdomen?

• PUPPP (Pruritic Urticarial Papules and Plaques of Pregnancy) (Correct answer)
• Pemphigoid gestationis
• Intrahepatic cholestasis of pregnancy
• Atopic eruption of pregnancy

Correct answer: PUPPP (Pruritic Urticarial Papules and Plaques of Pregnancy)

PUPPP (also called polymorphic eruption of pregnancy) classically begins in the abdominal striae of primigravida women in the third trimester, sparing the umbilicus.

Question 47: Which dermatoscopic structure is most associated with melanoma?

• Atypical pigment network (Correct answer)
• Milia-like cysts
• Comma vessels
• Arborizing vessels

Correct answer: Atypical pigment network

An atypical (irregular) pigment network with variable thickness and abrupt termination at the periphery is a key dermoscopic feature of melanoma.

Question 48: Which layer of the epidermis is responsible for cell division and renewal?

• Stratum corneum
• Stratum spinosum
• Stratum granulosum
• Stratum basale (Correct answer)

Correct answer: Stratum basale

The stratum basale contains mitotically active keratinocytes that continuously divide to renew the epidermis.

Question 49: Which topical antifungal works by inhibiting ergosterol synthesis through blockade of lanosterol 14α-demethylase?

• Ketoconazole (Correct answer)
• Ciclopirox
• Nystatin
• Terbinafine

Correct answer: Ketoconazole

Azole antifungals like ketoconazole inhibit cytochrome P450-dependent lanosterol 14α-demethylase, blocking ergosterol synthesis and disrupting the fungal cell membrane.

Question 50: Which actinic keratosis feature suggests highest risk of progression to invasive SCC?

• Flat pigmented AK
• AK on the forearm
• Hypertrophic/thick AK with induration and tenderness (Correct answer)
• Multiple thin AKs on the scalp

Correct answer: Hypertrophic/thick AK with induration and tenderness

Hypertrophic, indurated, or tender actinic keratoses have the highest risk of harboring or progressing to invasive SCC and warrant aggressive treatment or biopsy.

Question 51: What histological finding is characteristic of mycosis fungoides (cutaneous T-cell lymphoma)?

• Pautrier microabscesses with atypical lymphocytes in the epidermis (Correct answer)
• Granulomas with central caseation
• Acanthosis with parakeratosis
• Subepidermal clefting with eosinophils

Correct answer: Pautrier microabscesses with atypical lymphocytes in the epidermis

Pautrier microabscesses — collections of atypical cerebriform T-lymphocytes within the epidermis — are pathognomonic of mycosis fungoides on histology.

Question 52: What is a skin condition characterized by red lesions that resemble targets and is typically brought on by the herpes virus?

• erythema multiforme
• keratosis pilaris
• candidiasis
• hirsutism

The correct answer is Erythema Multiforme. This skin condition is characterized by distinctive 'target lesions' (red lesions with a darker center and a pale ring), and it is frequently triggered by infections, most notably the herpes simplex virus.

Question 53: What is the recommended surgical margin for a primary melanoma with Breslow thickness between 1.01–2.0 mm?

• 3 cm wide local excision
• 5 mm punch excision
• 1–2 cm wide local excision (Correct answer)
• 0.5 cm wide local excision

Correct answer: 1–2 cm wide local excision

Current guidelines recommend 1–2 cm surgical margins for melanomas with Breslow thickness between 1.01 and 2.0 mm to achieve adequate local control.

Question 54: Which dermatological sign—a positive Nikolsky sign—is characterized by what response when lateral pressure is applied to normal-appearing skin?

• Epidermal shearing and blister formation (Correct answer)
• Blanching of erythema
• Darkening of the lesion
• Induration of the skin

Correct answer: Epidermal shearing and blister formation

A positive Nikolsky sign occurs when gentle lateral pressure causes the epidermis to slide or shear off, indicating fragile epidermal cohesion as in pemphigus.

Question 55: Which type of skin cancer has the highest rate of metastasis?

• Sebaceous carcinoma
• Basal cell carcinoma
• Squamous cell carcinoma
• Merkel cell carcinoma (Correct answer)

Correct answer: Merkel cell carcinoma

Merkel cell carcinoma is a rare but aggressive neuroendocrine skin cancer with high rates of local recurrence, nodal spread, and distant metastasis.

Question 56: Calcineurin inhibitors (tacrolimus and pimecrolimus) are used as steroid-sparing agents for which condition?

• Actinic keratoses
• Psoriasis plaques on the trunk
• Atopic dermatitis, especially on the face and intertriginous areas (Correct answer)
• Seborrheic dermatitis

Correct answer: Atopic dermatitis, especially on the face and intertriginous areas

Topical calcineurin inhibitors block T-cell activation and are indicated for atopic dermatitis, particularly as steroid-sparing agents for sensitive areas like the face and skin folds.

Question 57: What is another word for intertrigo?

• Skin Fold Dermatitis (Correct answer)
• Vertigo
• Pyotraumatic Dermatitis
• Furunculosis

Correct answer: Skin Fold Dermatitis

Intertrigo is an inflammatory skin condition that occurs in skin folds where skin rubs against skin, leading to friction, moisture, and irritation. It is commonly referred to as skin fold dermatitis due to its location and nature.

Question 58: What feature of melanoma on dermoscopy is most specific for malignancy?

• Regular dermoscopic structures
• Symmetrical globules
• Blue-white veil overlying raised areas (Correct answer)
• Uniform pigment network

Correct answer: Blue-white veil overlying raised areas

The blue-white veil — an irregular, structureless, ground-glass blue area with overlying white haze — is a dermoscopic feature highly specific for invasive melanoma.

Question 59: What is the primary cell type responsible for the inflammatory response in contact dermatitis?

• Mast cells
• CD4+ T lymphocytes (Th1/Th2 cells) (Correct answer)
• Plasma cells
• Neutrophils

Correct answer: CD4+ T lymphocytes (Th1/Th2 cells)

Allergic contact dermatitis is a Type IV (delayed-type) hypersensitivity reaction mediated by sensitized CD4+ T lymphocytes responding to the hapten-carrier complex.

Question 60: A 45-year-old presents with a scaly, erythematous plaque with silver scale on the extensor surface of the elbow. The Auspitz sign is positive. What is the most likely diagnosis?

• Seborrheic dermatitis
• Psoriasis vulgaris (Correct answer)
• Pityriasis rosea
• Lichen planus

Correct answer: Psoriasis vulgaris

Auspitz sign (pinpoint bleeding when scale is removed) is characteristic of psoriasis vulgaris, commonly found on extensor surfaces.

Question 61: What is the most common type of skin cancer in the United States?

• Melanoma
• Basal cell carcinoma (BCC) (Correct answer)
• Merkel cell carcinoma
• Squamous cell carcinoma (SCC)

Correct answer: Basal cell carcinoma (BCC)

Basal cell carcinoma is the most common human malignancy, accounting for approximately 80% of all non-melanoma skin cancers and affecting millions of Americans annually.

Question 62: Which histological subtype of basal cell carcinoma carries the highest risk of recurrence and invasion?

• Pigmented BCC
• Morpheaform (sclerosing/infiltrative) BCC (Correct answer)
• Superficial BCC
• Nodular BCC

Correct answer: Morpheaform (sclerosing/infiltrative) BCC

Morpheaform BCC has indistinct clinical borders with finger-like projections extending well beyond the visible lesion, making it the most aggressive subtype with the highest recurrence rate.

Question 63: What is the primary mechanism of action of botulinum toxin A in cosmetic dermatology?

• Inhibits acetylcholine release at the neuromuscular junction causing temporary muscle paralysis (Correct answer)
• Blocks substance P to reduce inflammation
• Disrupts disulfide bonds in keratin filaments
• Stimulates collagen production in the dermis

Correct answer: Inhibits acetylcholine release at the neuromuscular junction causing temporary muscle paralysis

Botulinum toxin A cleaves SNAP-25, preventing acetylcholine vesicle fusion at the neuromuscular junction, thereby causing temporary flaccid paralysis of injected muscles.

Question 64: What term describes the genetic skin disorder characterized by absent or reduced melanin production due to tyrosinase deficiency?

• Chediak-Higashi syndrome
• Vitiligo
• Piebaldism
• Oculocutaneous albinism (Correct answer)

Correct answer: Oculocutaneous albinism

Oculocutaneous albinism results from mutations in genes such as TYR (tyrosinase), leading to absent or severely reduced melanin in skin, hair, and eyes.

Question 65: Which SPF value indicates protection against approximately 97% of UVB radiation?

• SPF 50
• SPF 30 (Correct answer)
• SPF 15
• SPF 100

Correct answer: SPF 30

SPF 30 blocks approximately 97% of UVB rays, SPF 50 blocks ~98%, and SPF 100 blocks ~99% — the incremental difference above SPF 30 is minimal.

Question 66: Which dermatophyte species is the most common cause of tinea capitis in the United States?

• Microsporum canis
• Epidermophyton floccosum
• Trichophyton tonsurans (Correct answer)
• Trichophyton rubrum

Correct answer: Trichophyton tonsurans

Trichophyton tonsurans is the predominant cause of tinea capitis in the US, especially in African American children.

Question 67: What is the most common primary malignant skin tumor worldwide by incidence?

• Merkel cell carcinoma
• Basal cell carcinoma (Correct answer)
• Squamous cell carcinoma
• Melanoma

Correct answer: Basal cell carcinoma

Basal cell carcinoma is the most common human cancer overall, accounting for approximately 80% of all non-melanoma skin cancers.

Question 68: What is the vehicle that determines the potency classification of topical corticosteroids?

• Concentration alone determines potency
• Molecular weight of the steroid
• The formulation (ointment > gel > cream > lotion > solution) significantly affects potency (Correct answer)
• pH of the preparation

Correct answer: The formulation (ointment > gel > cream > lotion > solution) significantly affects potency

The same corticosteroid molecule can have different potency classes depending on the vehicle — ointments provide the greatest occlusion and skin penetration, followed by gels, creams, and lotions.

Question 69: Which feature best distinguishes seborrheic keratosis from a melanoma?

• Pruritus and bleeding
• Stuck-on appearance with horn cysts visible on dermoscopy (Correct answer)
• Asymmetric borders and color variation
• Rapid growth over weeks

Correct answer: Stuck-on appearance with horn cysts visible on dermoscopy

Seborrheic keratosis has a characteristic 'stuck-on' waxy appearance with comedone-like openings (horn cysts) seen on dermoscopy, distinguishing it from melanoma.

Question 70: Which direct immunofluorescence pattern is characteristic of pemphigus vulgaris?

• Linear IgG and C3 at the basement membrane zone
• Granular IgA deposits in dermal papillae
• Granular IgM at the dermal-epidermal junction
• Intercellular IgG in a 'chicken wire' pattern (Correct answer)

Correct answer: Intercellular IgG in a 'chicken wire' pattern

Pemphigus vulgaris shows intercellular IgG deposits creating a 'chicken wire' or 'fish net' pattern throughout the epidermis due to anti-desmoglein autoantibodies.

Question 71: Which inflammatory cell type predominates in the histological findings of allergic contact dermatitis?

• Lymphocytes (Correct answer)
• Plasma cells
• Eosinophils
• Neutrophils

Correct answer: Lymphocytes

Allergic contact dermatitis is a type IV (delayed-type) hypersensitivity reaction mediated by T lymphocytes, which predominate in the perivascular dermal infiltrate.

Question 72: Seborrheic dermatitis preferentially affects which areas?

• Flexural creases and groin
• Lower legs and dorsal feet
• Scalp, nasolabial folds, and central chest (Correct answer)
• Dorsal hands and extensor surfaces

Correct answer: Scalp, nasolabial folds, and central chest

Seborrheic dermatitis affects sebum-rich areas including the scalp, face (nasolabial folds, eyebrows), and upper trunk due to Malassezia overgrowth.

Question 73: What is the correct depth of injection for hyaluronic acid filler used to treat nasolabial folds?

• Deep dermis to subcutaneous junction (Correct answer)
• Muscle belly
• Superficial epidermis
• Subperiosteal plane

Correct answer: Deep dermis to subcutaneous junction

Nasolabial fold correction with HA filler requires injection at the deep dermis to subcutaneous junction to provide volume support and lift without visibility of filler.

Question 74: What can be the Remnants of a pustule, vesicle, or bulla?

• Plaque
• Epidermal Collarette (Correct answer)
• Scale
• Cyst

Correct answer: Epidermal Collarette

An epidermal collarette is a circular rim of scale that represents the remnants of the roof of a ruptured pustule, vesicle, or bulla. It indicates a previous lesion that has healed or is in the process of healing, often seen in pyoderma.

Question 75: Which injection technique minimizes the risk of intravascular filler injection in the glabellar region?

• Aspiration before injection, small aliquots, low injection pressure, and superficial dermal placement (Correct answer)
• Deep subcutaneous injection with large bolus technique
• Rapid high-pressure injection
• Perpendicular needle insertion to periosteum

Correct answer: Aspiration before injection, small aliquots, low injection pressure, and superficial dermal placement

In the high-risk glabellar region, aspiration, small aliquot injection, low pressure, superficial placement, and knowledge of vascular anatomy help prevent catastrophic intravascular injection.

Question 76: Photosensitivity caused by tetracyclines is primarily classified as which type of reaction?

• Phototoxic (Correct answer)
• Photoallergic
• Chronic actinic dermatitis
• Polymorphous light eruption

Correct answer: Phototoxic

Tetracyclines cause phototoxic reactions that are dose-dependent and do not require prior sensitization, occurring in most exposed individuals.

Question 77: The term 'lichenification' refers to which morphological skin change caused by chronic rubbing or scratching?

• Loss of epidermis exposing the dermis
• Flat, non-palpable color change
• Thickened, exaggerated skin markings with a leathery texture (Correct answer)
• Fluid-filled cavity within the epidermis

Correct answer: Thickened, exaggerated skin markings with a leathery texture

Lichenification describes thickened, leathery skin with accentuated surface markings, resulting from prolonged rubbing or scratching in conditions like atopic dermatitis.

Question 78: The phrase 'herald patch' is the classic initial presentation of which common self-limited skin eruption?

• Pityriasis rosea (Correct answer)
• Guttate psoriasis
• Secondary syphilis
• Tinea corporis

Correct answer: Pityriasis rosea

Pityriasis rosea classically begins with a single large 'herald patch' followed days to weeks later by a widespread Christmas-tree pattern eruption.

Question 79: Solar elastosis is characterized by which histological finding in the dermis?

• Basophilic degeneration and clumping of elastic fibers (Correct answer)
• Mucin deposition in the reticular dermis
• Increased fibrotic collagen deposition
• Granulomatous inflammation with giant cells

Correct answer: Basophilic degeneration and clumping of elastic fibers

Solar elastosis results from chronic UV exposure causing abnormal production and degeneration of elastic fibers, which appear basophilic/amphophilic and clumped on H&E staining.

Question 80: Which topical medication is first-line for treating cradle cap (infantile seborrheic dermatitis) on the scalp?

• Coal tar preparations
• Gentle emollient oils and mild antifungal shampoos (Correct answer)
• Salicylic acid peels
• High-potency topical corticosteroids

Correct answer: Gentle emollient oils and mild antifungal shampoos

Cradle cap is managed with gentle emollient oils to loosen scales followed by mild ketoconazole or antifungal shampoos, reserving low-potency steroids for resistant cases.

Question 81: Which filler material provides the longest duration of effect among commonly used dermal fillers?

• Collagen fillers
• Poly-L-lactic acid (Sculptra) (Correct answer)
• Hyaluronic acid fillers
• Calcium hydroxylapatite (Radiesse)

Correct answer: Poly-L-lactic acid (Sculptra)

Poly-L-lactic acid (Sculptra) is a biostimulatory filler that stimulates neocollagenesis over months, with results lasting up to 2 years or more.

Question 82: Which skin neoplasm is linked to an increase in cell development in the epidermis' keratin layer brought on by pressure or friction?

• keratosis
• leukoplakia
• callus (Correct answer)
• keloid

Correct answer: callus

A callus is a thickened area of skin that develops in response to repeated pressure or friction. It is a protective mechanism where the epidermis, specifically the keratin layer, increases cell production to create a tougher, more resilient surface. Calluses are benign and are commonly found on the hands and feet.

Question 83: Photosensitivity reactions are a known adverse effect of which commonly prescribed antibiotic used for acne?

• Clindamycin
• Cephalexin
• Erythromycin
• Doxycycline (Correct answer)

Correct answer: Doxycycline

Doxycycline, a tetracycline antibiotic widely used for inflammatory acne, commonly causes phototoxic reactions — patients must be counseled to use broad-spectrum sunscreen and avoid prolonged sun exposure.

Question 84: A patient presents with targetoid lesions after starting trimethoprim-sulfamethoxazole. Mucosal involvement affects two sites. What is the diagnosis?

• Toxic epidermal necrolysis
• Stevens-Johnson syndrome (Correct answer)
• Erythema multiforme major
• Fixed drug eruption

Correct answer: Stevens-Johnson syndrome

Stevens-Johnson syndrome involves mucosal involvement at ≥2 sites with epidermal detachment affecting <10% of body surface area, often triggered by drugs.

Question 85: Tzanck smear showing multinucleated giant cells is characteristic of which condition?

• Impetigo
• Pemphigus vulgaris
• Molluscum contagiosum
• Herpes simplex or varicella-zoster infection (Correct answer)

Correct answer: Herpes simplex or varicella-zoster infection

A positive Tzanck smear showing multinucleated giant cells is diagnostic of herpetic infections, including both herpes simplex virus and varicella-zoster virus.

Question 86: Civatte bodies (colloid/hyaline bodies) are characteristic of which dermatological condition?

• Dermatitis herpetiformis
• Lichen planus (Correct answer)
• Psoriasis
• Pemphigus vulgaris

Correct answer: Lichen planus

Civatte bodies are apoptotic keratinocytes (eosinophilic globules) seen at the dermal-epidermal junction in lichen planus due to interface dermatitis.

Question 87: Which topical medication is first-line for rosacea papulopustular subtype?

• Topical metronidazole (Correct answer)
• Topical mupirocin
• Topical betamethasone
• Topical tretinoin

Correct answer: Topical metronidazole

Topical metronidazole is a first-line treatment for papulopustular rosacea due to its anti-inflammatory and antimicrobial properties.

Question 88: What is alopecia?

• Difficult for men to deal with
• Only full hair loss
• Full or partial hair loss (Correct answer)
• Never where you want it to be

Correct answer: Full or partial hair loss

Alopecia is the medical term for hair loss, which can manifest as either complete absence of hair in an area (full hair loss) or a thinning of hair (partial hair loss). It can affect any part of the body and have various underlying causes.

Question 89: Nikolsky's sign is positive in which of the following conditions?

• Dermatitis herpetiformis
• Pemphigus vulgaris (Correct answer)
• Bullous pemphigoid
• Epidermolysis bullosa acquisita

Correct answer: Pemphigus vulgaris

Nikolsky's sign — lateral pressure causing epidermal slippage — is positive in pemphigus vulgaris due to loss of keratinocyte cohesion from anti-desmoglein antibodies.

Question 90: The Koebner phenomenon refers to the appearance of skin lesions at sites of:

• Allergic reaction
• Trauma or injury (Correct answer)
• Sun exposure
• Bacterial infection

Correct answer: Trauma or injury

The Koebner (isomorphic) phenomenon occurs when skin disease appears at sites of trauma, classically seen in psoriasis, vitiligo, and lichen planus.

Question 91: Dapsone is used in dermatology primarily for which two conditions?

• Acne and rosacea
• Vitiligo and alopecia areata
• Dermatitis herpetiformis and leprosy (Correct answer)
• Psoriasis and eczema

Correct answer: Dermatitis herpetiformis and leprosy

Dapsone is the drug of choice for dermatitis herpetiformis and is a key component of multidrug therapy for leprosy, working through anti-inflammatory and antimicrobial mechanisms.

Question 92: Which anatomic structure marks the junction between the epidermis and dermis and plays a key role in anchoring the two layers?

• Rete pegs only
• Stratum granulosum
• Basement membrane zone (Correct answer)
• Papillary dermis capillaries

Correct answer: Basement membrane zone

The basement membrane zone (dermal-epidermal junction) contains hemidesmosomes, laminin, and type IV collagen that anchor the epidermis to the dermis.

Question 93: Photodynamic therapy (PDT) with aminolevulinic acid (ALA) is FDA-approved for treatment of which condition?

• Squamous cell carcinoma in situ (Bowen disease)
• Nodular basal cell carcinoma
• Sebaceous hyperplasia
• Actinic keratoses (Correct answer)

Correct answer: Actinic keratoses

PDT with ALA (Levulan) followed by blue or red light activation is FDA-approved for non-hyperkeratotic actinic keratoses on the face and scalp.

Question 94: What is the most common benign skin tumor in adults?

• Epidermal inclusion cyst
• Dermatofibroma
• Lipoma
• Seborrheic keratosis (Correct answer)

Correct answer: Seborrheic keratosis

Seborrheic keratosis is the most common benign epidermal tumor in adults, increasing in number and size with age and typically requiring no treatment.

Question 95: Squamous cell carcinoma arising in a chronic wound or scar is known as which eponymous carcinoma?

• Paget disease
• Spiegler tumor
• Marjolin ulcer (Correct answer)
• Bowen disease

Correct answer: Marjolin ulcer

Marjolin ulcer is SCC arising from chronic wounds, burn scars, osteomyelitis sinuses, or other areas of chronic inflammation, typically with an aggressive course and higher metastatic risk.

Question 96: Which rare genodermatosis causes blistering at the site of minor trauma due to mutations in structural proteins of the epidermis or basement membrane?

• Darier disease
• Ichthyosis vulgaris
• Hailey-Hailey disease
• Epidermolysis bullosa (Correct answer)

Correct answer: Epidermolysis bullosa

Epidermolysis bullosa encompasses a group of inherited disorders caused by mutations in keratin, laminin, or collagen VII genes, resulting in extreme skin fragility.

Question 97: What is the Breslow thickness threshold above which sentinel lymph node biopsy is routinely recommended for melanoma?

• 0.8 mm
• 1.5 mm
• 0.5 mm
• 1.0 mm (Correct answer)

Correct answer: 1.0 mm

SLNB is routinely recommended for melanomas >1.0 mm Breslow thickness; it may be considered for 0.8–1.0 mm lesions with high-risk features.

Question 98: What is the primary pathological finding in bullous pemphigoid?

• IgA deposits in dermal papillae
• T-cell mediated destruction of basal keratinocytes
• IgG autoantibodies targeting BP180 and BP230 at the dermoepidermal junction (Correct answer)
• IgG autoantibodies targeting desmoglein 1 and 3

Correct answer: IgG autoantibodies targeting BP180 and BP230 at the dermoepidermal junction

Bullous pemphigoid is caused by IgG autoantibodies against BP180 (collagen XVII) and BP230, proteins of the hemidesmosome at the dermoepidermal junction.

Question 99: Which US state became the first to ban commercial tanning beds for minors under 18, paving the way for similar legislation nationwide?

• Texas
• California (Correct answer)
• New York
• Florida

Correct answer: California

California became the first US state to ban indoor tanning for minors under 18 in 2011, citing increased melanoma risk.

Question 100: Mohs micrographic surgery is most appropriate for which type of skin cancer?

• Sebaceous carcinoma on the eyelid
• Thin superficial spreading melanoma on the trunk
• Dermatofibrosarcoma protuberans on the scalp
• High-risk basal cell carcinoma on the face with poorly defined borders (Correct answer)

Correct answer: High-risk basal cell carcinoma on the face with poorly defined borders

Mohs surgery is the gold standard for high-risk BCCs, particularly on the face (H-zone), with recurrent tumors, or poorly defined borders where tissue conservation is critical.

Question 101: Salicylic acid functions as a keratolytic agent by what mechanism?

• Inhibits prostaglandin synthesis reducing inflammation
• Activates proteases that cleave corneodesmosin
• Disrupts intercellular lipid bilayers causing desquamation of the stratum corneum (Correct answer)
• Chelates calcium ions disrupting desmosomes

Correct answer: Disrupts intercellular lipid bilayers causing desquamation of the stratum corneum

Salicylic acid solubilizes the intercellular cement substance of the stratum corneum, reducing corneocyte cohesion and promoting shedding of hyperkeratotic scale.

Question 102: Which neurocutaneous syndrome is characterized by café-au-lait macules, axillary freckling, and neurofibromas?

• Incontinentia pigmenti
• Sturge-Weber syndrome
• Neurofibromatosis type 1 (NF1) (Correct answer)
• Tuberous sclerosis complex

Correct answer: Neurofibromatosis type 1 (NF1)

NF1 (von Recklinghausen disease) is diagnosed by ≥6 café-au-lait macules, Lisch nodules, axillary/inguinal freckling, neurofibromas, and other features from autosomal dominant NF1 mutations.

Question 103: Subepidermal blisters with neutrophilic microabscesses in dermal papillae are histologically characteristic of which condition?

• Bullous pemphigoid
• Linear IgA bullous dermatosis
• Dermatitis herpetiformis (Correct answer)
• Pemphigus vulgaris

Correct answer: Dermatitis herpetiformis

Dermatitis herpetiformis shows subepidermal blisters with neutrophil-rich microabscesses at dermal papillae tips, corresponding to granular IgA deposits.

Question 104: What is the most common cause of tinea capitis in the United States?

• Microsporum canis
• Epidermophyton floccosum
• Trichophyton rubrum
• Trichophyton tonsurans (Correct answer)

Correct answer: Trichophyton tonsurans

Trichophyton tonsurans is responsible for the majority of tinea capitis cases in the US, particularly in school-aged children of African American descent.

Question 105: A child presents with a 'strawberry tongue,' desquamating rash, and perioral pallor. What organism is responsible?

• Neisseria meningitidis
• Haemophilus influenzae
• Staphylococcus aureus
• Group A Streptococcus (Correct answer)

Correct answer: Group A Streptococcus

Scarlet fever is caused by Group A Streptococcus producing erythrogenic toxins, leading to the classic rash and strawberry tongue.

Question 106: In which epidermal layer are melanocytes primarily located?

• Stratum granulosum
• Stratum basale (Correct answer)
• Stratum corneum
• Stratum spinosum

Correct answer: Stratum basale

Melanocytes reside in the stratum basale (basal layer), where they synthesize melanin and transfer it to surrounding keratinocytes via dendrites.

Question 107: Palisading granulomas with central necrobiosis of collagen and mucin are the histological hallmark of which condition?

• Foreign body granuloma
• Sarcoidosis
• Granuloma annulare (Correct answer)
• Lepromatous leprosy

Correct answer: Granuloma annulare

Granuloma annulare is characterized by palisading histiocytes surrounding central zones of degenerated collagen and mucin deposition in the dermis.

Question 108: Which structure within the hair follicle is responsible for generating the hair shaft and is often called the 'hair matrix'?

• The infundibulum
• The isthmus region
• The bulb at the base of the follicle (Correct answer)
• The arrector pili muscle

Correct answer: The bulb at the base of the follicle

The hair bulb contains rapidly dividing matrix cells that differentiate and keratinize to form the hair shaft, driven by signals from the dermal papilla.

Question 109: A patient with HIV develops painful, grouped vesicles along a unilateral thoracic dermatome. What is the treatment of choice?

• Oral doxycycline
• Topical acyclovir
• Oral valacyclovir (Correct answer)
• Intravenous amphotericin B

Correct answer: Oral valacyclovir

Herpes zoster in immunocompromised patients is treated with oral valacyclovir or famciclovir; IV acyclovir is reserved for severe or disseminated disease.

Question 110: Which condition is characterized by thickened, yellow-green nails with slow growth and is associated with lymphedema and pleural effusion?

• Yellow nail syndrome (Correct answer)
• Nail-patella syndrome
• Pachyonychia congenita
• Onychomycosis

Correct answer: Yellow nail syndrome

Yellow nail syndrome is a rare disorder characterized by yellow, thickened, slow-growing nails associated with lymphedema and respiratory manifestations.

Question 111: Which pigment gives sebaceous gland secretions their characteristic color and contributes to the yellow tint in aged skin?

• Lipofuscin
• Melanin
• Carotenoids (Correct answer)
• Bilirubin

Correct answer: Carotenoids

Dietary carotenoids accumulate in sebaceous secretions and subcutaneous fat, contributing to the yellowish tint seen in the skin.

Question 112: In dermatopathology, 'spongiosis' refers to which histological finding?

• Thickening of the stratum corneum
• Loss of cell-to-cell cohesion in the epidermis
• Intercellular edema within the epidermis (Correct answer)
• Thinning of the granular layer

Correct answer: Intercellular edema within the epidermis

Spongiosis is intercellular edema between keratinocytes, causing the epidermis to appear sponge-like on histology and is the hallmark of eczematous dermatitis.

Question 113: Which autoimmune blistering disease is characterized by IgG antibodies against desmoglein 1 and 3, affecting the epidermis?

• Pemphigus vulgaris (Correct answer)
• Bullous pemphigoid
• Epidermolysis bullosa acquisita
• Dermatitis herpetiformis

Correct answer: Pemphigus vulgaris

Pemphigus vulgaris features IgG autoantibodies against desmoglein 3 (mucosal) and desmoglein 1 (cutaneous), causing acantholysis and suprabasal blisters.

Question 114: Parakeratosis is defined as which histological finding?

• Increased thickness of the stratum spinosum
• Retention of nuclei within the stratum corneum (Correct answer)
• Neutrophil infiltration within the epidermis
• Absence of the stratum granulosum

Correct answer: Retention of nuclei within the stratum corneum

Parakeratosis is the retention of nuclei in the stratum corneum, indicating abnormal keratinization and rapid epidermal turnover, as seen in psoriasis.

Question 115: What kind of cyst typically develops on the vulva, scrotum, and scalp and includes yellowish sebum?

• ulcer
• vesicle
• papule
• sebaceous cyst (Correct answer)

Correct answer: sebaceous cyst

A sebaceous cyst, also known as an epidermoid cyst, is a common non-cancerous cyst that arises from a blocked sebaceous gland or hair follicle. These cysts typically contain a yellowish, cheesy, or oily substance (sebum) and are frequently found on areas with many sebaceous glands, such as the scalp, face, neck, back, and sometimes the vulva or scrotum.

Question 116: Epidermolysis bullosa (EB) is caused by mutations in genes encoding which structural proteins?

• Filaggrin and involucrin
• Elastin and fibrillin
• Keratin, laminin, collagen VII, or other structural proteins of the dermoepidermal junction (Correct answer)
• Desmoglein and desmocollin

Correct answer: Keratin, laminin, collagen VII, or other structural proteins of the dermoepidermal junction

EB is a heterogeneous group of mechanobullous disorders caused by mutations in genes encoding structural proteins including keratins (simplex), laminin-332 (junctional), or collagen VII (dystrophic).

Question 117: Which type of hypersensitivity reaction underlies allergic contact dermatitis?

• Type III (immune complex)
• Type II (cytotoxic)
• Type I (IgE-mediated)
• Type IV (delayed-type) (Correct answer)

Correct answer: Type IV (delayed-type)

Allergic contact dermatitis is a Type IV (cell-mediated, delayed-type) hypersensitivity reaction involving sensitized T lymphocytes.

Question 118: PD-1 checkpoint inhibitors (nivolumab, pembrolizumab) are approved for which stage of melanoma?

• In situ melanoma
• Advanced/metastatic melanoma and high-risk resected stage III/IV adjuvant therapy (Correct answer)
• Stage I thin melanoma
• Lentigo maligna melanoma only

Correct answer: Advanced/metastatic melanoma and high-risk resected stage III/IV adjuvant therapy

Anti-PD-1 immunotherapy is approved for unresectable or metastatic melanoma and as adjuvant therapy for high-risk resected stage III and stage IV melanoma to reduce recurrence.

Question 119: A 'Grenz zone' on dermatopathology refers to which histological finding?

• The zone of acanthosis seen in psoriasis
• The normal papillary dermis in unaffected skin
• A clear halo surrounding a tumor nest
• A band of spared papillary dermis between the epidermis and a dermal infiltrate (Correct answer)

Correct answer: A band of spared papillary dermis between the epidermis and a dermal infiltrate

The Grenz zone is a narrow band of normal papillary dermis separating the overlying epidermis from the underlying inflammatory or neoplastic infiltrate, often seen in lepromatous leprosy and some lymphomas.

Question 120: What does yellowing of the skin indicate?

• hyperkalemia
• hyperuricemia
• hyporeninemia
• hyperbilirubinemia (Correct answer)

Correct answer: hyperbilirubinemia

Yellowing of the skin, known as jaundice, is a clinical sign of hyperbilirubinemia, which is an excess of bilirubin in the blood. Bilirubin is a yellow pigment produced during the breakdown of red blood cells. Elevated levels can indicate liver disease, bile duct obstruction, or excessive red blood cell destruction.

Question 121: Which skin condition is characterized by silvery-white plaques with well-defined borders most commonly found on the elbows and knees?

• Rosacea
• Eczema
• Vitiligo
• Psoriasis (Correct answer)

Correct answer: Psoriasis

Psoriasis presents as thick, silvery-white scaly plaques with sharply demarcated borders, classically on extensor surfaces like elbows and knees.

Question 122: What makes ARF different from FAD?

• GI Signs (Correct answer)
• Scratching of muzzle
• Papules
• Excoriations

Correct answer: GI Signs

ARF (Atopic-like Reaction to Food) is a food allergy, and unlike FAD (Flea Allergy Dermatitis) which primarily causes skin irritation, ARF often presents with gastrointestinal (GI) signs such as vomiting, diarrhea, or changes in appetite, in addition to dermatological symptoms.

Question 123: The 'saw-tooth' pattern of rete ridges on skin histology is most characteristic of which condition?

• Psoriasis
• Seborrheic dermatitis
• Lichen planus (Correct answer)
• Systemic lupus erythematosus

Correct answer: Lichen planus

Lichen planus shows irregular, saw-tooth shaped rete ridges with a band-like lymphocytic infiltrate hugging the dermal-epidermal junction.

Question 124: What is intralesional triamcinolone acetonide most commonly used to treat in dermatology?

• Sebaceous cysts
• Basal cell carcinoma
• Keloids and hypertrophic scars (Correct answer)
• Epidermoid tumors

Correct answer: Keloids and hypertrophic scars

Intralesional triamcinolone acetonide is the first-line treatment for keloids and hypertrophic scars, reducing collagen synthesis and inducing collagenase activity to flatten the scar.

Question 125: What is the most common site of origin for lentigo maligna melanoma?

• Acral surfaces of hands and feet
• Posterior trunk
• Sun-damaged skin of the head and neck in elderly patients (Correct answer)
• Mucosal surfaces

Correct answer: Sun-damaged skin of the head and neck in elderly patients

Lentigo maligna melanoma develops from lentigo maligna (melanoma in situ) on chronically sun-damaged skin, most commonly on the face of elderly individuals.

Question 126: What is the recommended first-line systemic treatment for severe atopic dermatitis in adults when topical therapy fails?

• Dupilumab (IL-4Rα biologic) (Correct answer)
• Methotrexate
• Systemic cyclosporine
• Oral prednisone

Correct answer: Dupilumab (IL-4Rα biologic)

Dupilumab is now the preferred first-line systemic agent for moderate-to-severe atopic dermatitis in adults, offering superior efficacy and safety compared to traditional immunosuppressants.

Question 127: The Darier sign, elicited by stroking a lesion causing it to urticate and become raised, is pathognomonic for which condition?

• Lichen planus
• Mastocytosis (urticaria pigmentosa) (Correct answer)
• Dermatographism
• Bullous pemphigoid

Correct answer: Mastocytosis (urticaria pigmentosa)

Darier sign reflects mast cell degranulation in urticaria pigmentosa (cutaneous mastocytosis) upon physical stroking of the lesion.

Question 128: Gianotti-Crosti syndrome (papular acrodermatitis of childhood) is most commonly associated with which viral infection?

• Cytomegalovirus
• Hepatitis B virus
• Parvovirus B19
• Epstein-Barr virus (EBV) (Correct answer)

Correct answer: Epstein-Barr virus (EBV)

While historically associated with hepatitis B, Gianotti-Crosti syndrome in the US is now most commonly triggered by EBV infection, presenting with papular eruption on the face and extremities.

Question 129: The Fitzpatrick scale, developed in 1975, classifies human skin into how many phototypes?

• Six (Correct answer)
• Four
• Eight
• Ten

Correct answer: Six

Thomas Fitzpatrick developed a six-type scale (I–VI) to classify skin response to UV radiation based on pigmentation and burn/tan tendency.

Question 130: Which of the three skin layers contains the most fat and is therefore the thickest?

• epithelium
• subcutaneous tissue (Correct answer)
• epidermis
• dermis

Correct answer: subcutaneous tissue

The subcutaneous tissue, also known as the hypodermis, is the deepest layer of the skin. It is primarily composed of adipose (fat) tissue and loose connective tissue. This layer serves as an insulator, shock absorber, and energy reserve, making it typically the thickest layer of the skin.

Question 131: Which finding on histopathology is pathognomonic for psoriasis?

• Munro microabscesses in the stratum corneum (Correct answer)
• Subepidermal blister with neutrophils
• Spongiosis with eosinophils
• Dyskeratotic cells at all levels

Correct answer: Munro microabscesses in the stratum corneum

Munro microabscesses — collections of neutrophils in the stratum corneum — are a pathognomonic histological feature of psoriasis.

Question 132: What kind of follicles do fur-bearing animals have?

• Simple
• Compound (Correct answer)
• Intermediate
• Fuzzy

Correct answer: Compound

Fur-bearing animals, such as dogs and cats, typically possess compound hair follicles. These follicles are unique because they produce multiple hairs (a primary guard hair and several secondary undercoat hairs) from a single pore, contributing to their dense fur coat.

Question 133: A teenager presents with grouped erythematous papules and nodules along the jawline and perioral area. Which hormonal influence is most implicated?

• Elevated cortisol from stress
• Androgens stimulating sebaceous gland activity and sebum production (Correct answer)
• Growth hormone
• Estrogen dominance

Correct answer: Androgens stimulating sebaceous gland activity and sebum production

Teenage acne along the jawline and lower face is driven by androgen-stimulated sebaceous gland hypertrophy and increased sebum production, particularly during puberty.

Question 134: Which dermatological condition is associated with Nikolsky sign — skin separation with lateral pressure?

• Pemphigus vulgaris (Correct answer)
• Dermatitis herpetiformis
• Linear IgA bullous dermatosis
• Bullous pemphigoid

Correct answer: Pemphigus vulgaris

A positive Nikolsky sign, where gentle lateral pressure causes skin to shear and blister, is classically associated with pemphigus vulgaris due to loss of intraepidermal cohesion.

Question 135: Which congenital melanocytic nevus size poses the greatest risk of malignant melanoma transformation?

• Small CMN (<1.5 cm)
• Giant CMN (>20 cm in adult equivalent size) (Correct answer)
• Medium CMN (1.5–19.9 cm)
• Speckled lentiginous nevus

Correct answer: Giant CMN (>20 cm in adult equivalent size)

Giant congenital melanocytic nevi (>20 cm) carry the highest lifetime risk of melanoma transformation (estimated 5–10%) and are also associated with neurocutaneous melanocytosis.

Question 136: What histological hallmark differentiates Bowen disease (SCC in situ) from invasive SCC?

• Full-thickness epidermal dysplasia without invasion through the basement membrane (Correct answer)
• Lymphovascular invasion
• Keratin pearl formation
• Perineural invasion

Correct answer: Full-thickness epidermal dysplasia without invasion through the basement membrane

Bowen disease shows full-thickness dysplasia of the epidermis with preserved basement membrane — by definition, carcinoma in situ has not breached the basement membrane to invade the dermis.

Question 137: Xeroderma pigmentosum (XP) results from defects in which cellular repair mechanism?

• Base excision repair
• Homologous recombination
• Nucleotide excision repair (NER) of UV-induced DNA damage (Correct answer)
• Mismatch repair

Correct answer: Nucleotide excision repair (NER) of UV-induced DNA damage

XP is caused by inherited mutations in nucleotide excision repair genes, leaving UV-induced pyrimidine dimers unrepaired, leading to early and multiple skin cancers and photosensitivity.

Question 138: What is the pathognomonic skin finding of Kawasaki disease in children?

• Target lesions on the trunk and extremities
• Polymorphous exanthem with desquamation of fingertips in the recovery phase (Correct answer)
• Vesicular eruption on palms and soles
• Palpable purpura on the lower extremities

Correct answer: Polymorphous exanthem with desquamation of fingertips in the recovery phase

Kawasaki disease features a polymorphous rash plus desquamation of the fingertips and toes beginning in the periungual region during the subacute phase (10–25 days after fever onset).

Question 139: Which laser type is considered the gold standard for treating port-wine stains?

• Pulsed dye laser (585/595 nm) (Correct answer)
• Alexandrite laser
• Fractional CO2 laser
• Q-switched Nd:YAG laser

Correct answer: Pulsed dye laser (585/595 nm)

The pulsed dye laser, which targets oxyhemoglobin at 585 or 595 nm, is the treatment of choice for port-wine stains and other vascular lesions using the principle of selective photothermolysis.

Question 140: What is the first-line treatment for onychomycosis confirmed by positive fungal culture?

• Oral terbinafine (Correct answer)
• Topical clotrimazole
• Oral fluconazole
• Topical ciclopirox

Correct answer: Oral terbinafine

Oral terbinafine for 12 weeks is first-line for toenail onychomycosis due to its high cure rate and fungicidal mechanism against dermatophytes.

Question 141: What is the name of a crack or groove-like sore?

• polyp
• nodule
• fissure (Correct answer)
• ulcer

Correct answer: fissure

In dermatology, a fissure is defined as a linear crack or break in the skin that extends into the dermis. These lesions are often painful and can occur in areas of thickened, dry, or inflamed skin. Unlike an ulcer, which is a deeper open sore, a fissure is typically a narrow, groove-like defect.

Question 142: What is the most common skin condition in neonates presenting as erythematous macules with white or yellow papulopustules on an otherwise healthy newborn?

• Erythema toxicum neonatorum (Correct answer)
• Transient neonatal pustular melanosis
• Neonatal acne
• Miliaria crystallina

Correct answer: Erythema toxicum neonatorum

Erythema toxicum neonatorum is a benign, self-limiting eruption in healthy term newborns characterized by erythematous macules and papulopustules filled with eosinophils, resolving within 1–2 weeks.

Question 143: Tinea versicolor is caused by which organism?

• Candida albicans
• Epidermophyton floccosum
• Malassezia furfur (Correct answer)
• Trichophyton rubrum

Correct answer: Malassezia furfur

Tinea versicolor (pityriasis versicolor) is caused by the dimorphic yeast Malassezia furfur, part of normal skin flora.

Question 144: Impetigo caused by Staphylococcus aureus most characteristically produces which type of lesion?

• Honey-colored crusted lesions and bullae from exfoliative toxins (Correct answer)
• Deep nodular abscesses
• Erythematous targetoid plaques
• Vesicles following a dermatomal pattern

Correct answer: Honey-colored crusted lesions and bullae from exfoliative toxins

Staphylococcal impetigo produces the classic honey-colored crusted lesions; bullous impetigo results from exfoliative toxins A and B causing superficial epidermal cleavage at the granular layer.

Question 145: IL-17A inhibitors (secukinumab, ixekizumab) are approved for which dermatological condition?

• Hidradenitis suppurativa
• Moderate-to-severe plaque psoriasis (Correct answer)
• Atopic dermatitis
• Alopecia areata

Correct answer: Moderate-to-severe plaque psoriasis

Secukinumab and ixekizumab target IL-17A, a key downstream cytokine in the IL-23/Th17 axis, and are FDA-approved for moderate-to-severe plaque psoriasis with excellent efficacy.

Question 146: Which Nobel Prize-winning discovery led to widespread use of UV radiation in dermatology?

• Niels Finsen's phototherapy for lupus vulgaris (Correct answer)
• Marie Curie's discovery of radium
• Wilhelm Röntgen's X-rays
• Alexander Fleming's penicillin

Correct answer: Niels Finsen's phototherapy for lupus vulgaris

Niels Finsen won the 1903 Nobel Prize in Medicine for treating lupus vulgaris with concentrated UV light, founding phototherapy.

Question 147: What is the approximate total surface area of the skin in an average adult human?

• 2.5–3 square meters
• 3–4 square meters
• 1.5–2 square meters (Correct answer)
• 0.5–1 square meter

Correct answer: 1.5–2 square meters

The adult human skin covers approximately 1.5–2 square meters, making it the body's largest organ.

Question 148: The skin's vascular layer is called the?

• hypodermis
• dermis (Correct answer)
• epidermis
• stratum corneum unguis

Correct answer: dermis

The dermis is the middle layer of the skin, located beneath the epidermis. It is rich in blood vessels, nerves, hair follicles, and sweat glands, making it the primary vascular layer responsible for nourishing the skin and providing its structural integrity.

Question 149: A 30-year-old woman presents with periorbital heliotrope rash and Gottron's papules over the knuckles. What is the most likely diagnosis?

• Dermatomyositis (Correct answer)
• Psoriatic arthritis
• Mixed connective tissue disease
• Systemic lupus erythematosus

Correct answer: Dermatomyositis

Heliotrope rash and Gottron's papules are pathognomonic features of dermatomyositis.

Question 150: Verocay bodies are a histological feature associated with which cutaneous tumor?

• Neurofibroma
• Schwannoma (neurilemmoma) (Correct answer)
• Dermatofibroma
• Granular cell tumor

Correct answer: Schwannoma (neurilemmoma)

Verocay bodies are palisading arrangements of Schwann cell nuclei around acellular fibrillar material (Antoni A areas), pathognomonic of schwannoma.

Question 151: Which histological feature best distinguishes superficial spreading melanoma from a benign compound nevus?

• Pagetoid spread of melanocytes into upper epidermal layers (Correct answer)
• Nesting of melanocytes at the dermal-epidermal junction
• Presence of melanin pigment
• Presence of dermal melanocytes

Correct answer: Pagetoid spread of melanocytes into upper epidermal layers

Pagetoid spread refers to single melanocytes or nests ascending into the upper epidermis, a hallmark of melanoma not seen in benign nevi.

Question 152: Which condition presents with comedones, papules, pustules, and nodules primarily on the face, chest, and back?

• Folliculitis
• Perioral dermatitis
• Rosacea
• Acne vulgaris (Correct answer)

Correct answer: Acne vulgaris

Acne vulgaris involves follicular plugging (comedones) that progress to inflammatory papules, pustules, and nodules on sebaceous gland-rich areas of the face, chest, and back.

Question 153: Which of the following conditions is caused by a fungus?

• tinea capitis (Correct answer)
• keratosis
• lichen planus
• suborrhea

Correct answer: tinea capitis

Tinea capitis is a fungal infection that specifically affects the scalp and hair shafts, commonly known as ringworm of the scalp. It is caused by dermatophytes, a type of fungus that feeds on keratin. The other options listed are not primarily caused by fungal pathogens.

Question 154: A severe outbreak of extremely itchy papules or wheals is referred to as?

• acne vulgaris
• urticaria (Correct answer)
• psoriasis
• pityriasis rosea

Correct answer: urticaria

Urticaria, commonly known as hives, is characterized by a severe outbreak of extremely itchy, raised, red, or skin-colored welts (wheals) or papules on the skin. These lesions can appear suddenly and often disappear within hours, only to reappear elsewhere. It is typically an allergic reaction or a response to various triggers.

Question 155: What is the name of the brown-black skin pigment that is transferred to the other epidermal cells and gives the skin its color?

• albumin
• melanin (Correct answer)
• collagen
• keratin

Correct answer: melanin

Melanin is the primary pigment responsible for skin, hair, and eye color. It is produced by specialized cells called melanocytes in the epidermis and is then transferred to other epidermal cells. Melanin plays a crucial role in protecting the skin from harmful ultraviolet (UV) radiation by absorbing it.

Question 156: A patient presents with discrete, flat-topped, polygonal, violaceous papules on the wrists. What is the most likely diagnosis?

• Secondary syphilis
• Pityriasis rosea
• Psoriasis
• Lichen planus (Correct answer)

Correct answer: Lichen planus

Lichen planus classically presents with the '6 P's': pruritic, planar, polygonal, purple papules and plaques.

Question 157: What is the most serious adverse effect associated with long-term use of high-potency topical corticosteroids?

• Systemic hypertension
• Skin atrophy with telangiectasias and striae (Correct answer)
• Adrenal suppression in adults
• Contact sensitization

Correct answer: Skin atrophy with telangiectasias and striae

Prolonged use of high-potency topical steroids causes skin atrophy, striae distensae, telangiectasias, and purpura due to reduced collagen synthesis and thinning of all skin layers.

Question 158: Dermatitis herpetiformis is strongly associated with which systemic condition?

• Inflammatory bowel disease
• Crohn disease
• Celiac disease (gluten-sensitive enteropathy) (Correct answer)
• Systemic lupus erythematosus

Correct answer: Celiac disease (gluten-sensitive enteropathy)

Dermatitis herpetiformis is the cutaneous manifestation of celiac disease, with IgA deposits in dermal papillae triggered by gluten sensitivity.

Question 159: A newborn presents with vesicles and pustules on an erythematous base distributed over the trunk, face, and extremities. Smear shows eosinophils. What is the diagnosis?

• Staphylococcal scalded skin syndrome
• Neonatal herpes simplex
• Erythema toxicum neonatorum (Correct answer)
• Transient neonatal pustular melanosis

Correct answer: Erythema toxicum neonatorum

Erythema toxicum neonatorum is a benign self-limiting eruption in newborns characterized by eosinophils on smear.

Question 160: Which connective tissue disorder classically presents with a heliotrope rash around the eyes and Gottron's papules over the knuckles?

• Systemic lupus erythematosus
• Dermatomyositis (Correct answer)
• Mixed connective tissue disease
• Systemic sclerosis

Correct answer: Dermatomyositis

Dermatomyositis features a violaceous heliotrope rash on eyelids and Gottron's papules over the metacarpophalangeal joints, associated with proximal muscle weakness.

Question 161: Dermatitis herpetiformis is characterized by deposits of which immunoglobulin in the dermal papillae?

• IgA (Correct answer)
• IgE
• IgG
• IgM

Correct answer: IgA

Dermatitis herpetiformis shows granular IgA deposits in the dermal papillae on direct immunofluorescence, associated with celiac disease.

Question 162: What is the ABCDE rule used to evaluate in dermatology?

• Age, Biopsy, Curettage, Dermoscopy, Excision
• Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution (Correct answer)
• Appearance, Bleeding, Crust, Diameter, Erythema
• Atopy, Barrier dysfunction, Contact allergy, Dryness, Erythema

Correct answer: Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution

The ABCDE criteria — Asymmetry, Border irregularity, Color variation, Diameter greater than 6mm, and Evolution — are used to assess pigmented lesions for potential melanoma.

Question 163: A patient taking methotrexate for psoriasis develops oral ulcers and cytopenias. Which supplement should be co-administered to reduce toxicity?

• Vitamin D
• Zinc
• Folic acid (Correct answer)
• Vitamin B12

Correct answer: Folic acid

Folic acid supplementation reduces methotrexate-related side effects including mucositis and bone marrow suppression without significantly reducing efficacy.

Question 164: Which skin condition, historically called 'the great imitator,' can mimic virtually any dermatological disease in its secondary stage?

• Systemic lupus erythematosus
• Pityriasis rosea
• Secondary syphilis (Correct answer)
• Drug hypersensitivity syndrome

Correct answer: Secondary syphilis

Secondary syphilis produces a wide variety of skin manifestations—maculopapular rashes, condylomata lata, alopecia—earning syphilis the nickname 'the great imitator.'

Question 165: Which type of hypersensitivity reaction is responsible for allergic contact dermatitis?

• Type I (IgE-mediated)
• Type II (cytotoxic)
• Type IV (cell-mediated) (Correct answer)
• Type III (immune complex)

Correct answer: Type IV (cell-mediated)

Allergic contact dermatitis is a Type IV delayed hypersensitivity reaction mediated by sensitized T lymphocytes, typically occurring 48–72 hours after exposure.

Question 166: Both clotrimazole and nystatin are?

• topical antifungals (Correct answer)
• used to treat eczema
• topical antibiotics
• anti-itch creams

Correct answer: topical antifungals

Clotrimazole and nystatin are both well-known medications used to treat fungal infections. They are commonly available as topical creams, ointments, or powders and work by inhibiting the growth of fungi on the skin or mucous membranes. They are effective against a wide range of fungal pathogens.

Question 167: Which type of non-melanoma skin cancer is most commonly seen in organ transplant recipients on long-term immunosuppression?

• Sebaceous carcinoma
• Basal cell carcinoma
• Merkel cell carcinoma
• Squamous cell carcinoma (SCC) (Correct answer)

Correct answer: Squamous cell carcinoma (SCC)

Immunosuppressed transplant recipients develop SCC at dramatically higher rates (65–250 times higher) than the general population, with SCC outnumbering BCC — the reverse of the normal ratio.

Question 168: Which histological finding is considered pathognomonic of psoriasis?

• Munro microabscesses (Correct answer)
• Pautrier microabscesses
• Civatte bodies
• Flame figures

Correct answer: Munro microabscesses

Munro microabscesses are collections of neutrophils within the parakeratotic stratum corneum and are pathognomonic of psoriasis.

Question 169: What skin findings are associated with celiac disease beyond dermatitis herpetiformis?

• Aphthous ulcers, angular cheilitis, and alopecia (Correct answer)
• Erythema nodosum and pyoderma gangrenosum
• Psoriasis and vitiligo
• Acanthosis nigricans and ichthyosis

Correct answer: Aphthous ulcers, angular cheilitis, and alopecia

Celiac disease is associated with multiple cutaneous manifestations including recurrent aphthous ulcers, angular cheilitis from nutritional deficiencies, and alopecia.

Question 170: Which of the following conditions also goes by the name "ringworm"?

• herpes simplex
• impetigo
• tinea corporis (Correct answer)
• folliculitis

Correct answer: tinea corporis

Tinea corporis is the medical term for ringworm of the body. It is a common fungal infection that causes a red, itchy, circular rash with raised edges, often resembling a ring. Despite its name, ringworm is not caused by a worm but by dermatophyte fungi that thrive on keratinized tissues.

Question 171: What is the hallmark clinical feature of atopic dermatitis (eczema) in adults?

• Depigmented macules on sun-exposed skin
• Lichenification and pruritus in flexural areas (Correct answer)
• Vesicular eruption on palms and soles
• Annular scaling patches on the trunk

Correct answer: Lichenification and pruritus in flexural areas

Adult atopic dermatitis typically presents with lichenification and intense itching in flexural areas such as the antecubital and popliteal fossae.

Question 172: What is the role of dermoscopy (dermatoscopy) in skin cancer diagnosis?

• Spectroscopic analysis of melanin content
• Magnified visualization of subsurface skin structures to improve diagnostic accuracy of pigmented lesions (Correct answer)
• Real-time imaging of dermal collagen fibers
• In vivo confocal microscopy of cellular architecture

Correct answer: Magnified visualization of subsurface skin structures to improve diagnostic accuracy of pigmented lesions

Dermoscopy uses polarized or immersion light to visualize structures in the epidermis and superficial dermis invisible to the naked eye, significantly improving melanoma detection rates.

Question 173: Which sunscreen ingredient provides the broadest UVA protection and is commonly used in US formulations?

• Homosalate
• Oxybenzone
• Avobenzone (Parsol 1789) (Correct answer)
• Octinoxate

Correct answer: Avobenzone (Parsol 1789)

Avobenzone is the only FDA-approved organic UV filter providing full UVA protection (320–400 nm) but requires photostabilizers (like octocrylene) as it degrades with UV exposure.

Question 174: Koebner phenomenon — appearance of lesions along lines of trauma — is classically seen in which condition?

• Psoriasis (Correct answer)
• Seborrheic dermatitis
• Atopic dermatitis
• Acne vulgaris

Correct answer: Psoriasis

The Koebner (isomorphic) phenomenon, where new psoriatic plaques develop at sites of skin trauma or injury, is a hallmark feature of psoriasis.

Question 175: What is the term for a lack of colour in the skin?

• melanism
• xanthoderma
• acanthosis nigricans
• albinism (Correct answer)

Correct answer: albinism

Albinism is a congenital condition characterized by a complete or partial absence of pigment in the skin, hair, and eyes. This lack of melanin, the pigment responsible for color, results in very pale skin, white hair, and often light-colored eyes. It is a genetic disorder affecting melanin production pathways.

Question 176: What historical skin treatment, involving wrapping patients in cloth soaked in coal tar, was standard therapy for psoriasis before modern biologics?

• Goeckerman regimen (Correct answer)
• PUVA therapy
• Darier technique
• Ingram method

Correct answer: Goeckerman regimen

The Goeckerman regimen combined crude coal tar application with UV light exposure and was a mainstay psoriasis treatment for decades.

Question 177: 'Interface dermatitis' describes inflammatory damage primarily at which anatomical site?

• At the dermal-epidermal junction (Correct answer)
• Within the mid-dermis
• Between the dermis and follicular epithelium
• Between the dermis and subcutaneous fat

Correct answer: At the dermal-epidermal junction

Interface dermatitis refers to a lichenoid inflammatory pattern at the dermal-epidermal junction, causing vacuolar change or band-like infiltrate, as seen in lichen planus and lupus.

Question 178: Which laser is specifically used for tattoo removal based on the principle of selective photothermolysis?

• Q-switched Nd:YAG, alexandrite, or ruby laser (Correct answer)
• CO2 fractional laser
• Pulsed dye laser
• Diode laser

Correct answer: Q-switched Nd:YAG, alexandrite, or ruby laser

Q-switched lasers (Nd:YAG 1064/532 nm, alexandrite 755 nm, ruby 694 nm) deliver nanosecond pulses that fragment tattoo ink particles into smaller pieces cleared by macrophages.

Question 179: Extramammary Paget disease most commonly affects which anatomical sites?

• Axillae and neck
• Face and scalp
• Vulva, perianal region, and scrotum (Correct answer)
• Trunk and extremities

Correct answer: Vulva, perianal region, and scrotum

Extramammary Paget disease presents as erythematous, eczematous plaques with large clear (Paget) cells and may be associated with an underlying adnexal or visceral adenocarcinoma.

Question 180: Infantile hemangiomas reach their peak size at approximately what age?

• 3–5 months of age (Correct answer)
• 12–18 months of age
• 2–3 years of age
• Birth

Correct answer: 3–5 months of age

Infantile hemangiomas are absent or barely visible at birth, proliferate rapidly in the first 3–5 months of life reaching peak size, then slowly involute over years.

Question 181: A patient presents with diffuse hair shedding 3 months after a major surgery. What type of alopecia is this?

• Alopecia areata
• Androgenetic alopecia
• Anagen effluvium
• Telogen effluvium (Correct answer)

Correct answer: Telogen effluvium

Telogen effluvium occurs 2–4 months after a physiological stressor (surgery, illness, childbirth), causing premature shift of hair follicles into the telogen phase.

Question 182: What is the primary mechanism by which benzoyl peroxide treats acne?

• Releases free oxygen radicals that are bactericidal against Cutibacterium acnes (Correct answer)
• Modulates toll-like receptor 2 signaling
• Blocks androgen receptors in sebaceous glands
• Inhibits 5-alpha reductase reducing sebum production

Correct answer: Releases free oxygen radicals that are bactericidal against Cutibacterium acnes

Benzoyl peroxide is bactericidal against C. acnes through the release of reactive oxygen species, and critically, it does not induce antibiotic resistance.

Question 183: Which systemic medication requires monthly pregnancy tests and two forms of contraception due to severe teratogenicity?

• Hydroxychloroquine
• Dapsone
• Isotretinoin (Correct answer)
• Methotrexate

Correct answer: Isotretinoin

Isotretinoin is highly teratogenic, causing severe fetal malformations, and requires enrollment in the iPLEDGE program with mandatory monthly pregnancy testing and dual contraception.

Question 184: Which of the following best describes the mechanism of action of isotretinoin in treating acne?

• Increases epidermal turnover
• Blocks androgen receptors in follicles
• Inhibits bacterial protein synthesis
• Reduces sebaceous gland size and sebum production (Correct answer)

Correct answer: Reduces sebaceous gland size and sebum production

Isotretinoin permanently reduces sebaceous gland size by up to 90%, dramatically decreasing sebum production and normalizing follicular keratinization.

Question 185: Which immunoglobulin is primarily found at the dermal-epidermal junction in bullous pemphigoid?

• IgG (Correct answer)
• IgA
• IgM
• IgE

Correct answer: IgG

Bullous pemphigoid is characterized by IgG autoantibodies targeting BP180 and BP230 antigens at the dermal-epidermal junction.

Question 186: Merkel cell carcinoma is a neuroendocrine tumor associated with which viral pathogen?

• Human herpesvirus 8 (HHV-8)
• Merkel cell polyomavirus (MCPyV) (Correct answer)
• Epstein-Barr virus (EBV)
• Human papillomavirus (HPV)

Correct answer: Merkel cell polyomavirus (MCPyV)

Merkel cell polyomavirus DNA is integrated in approximately 80% of Merkel cell carcinomas, and viral oncoproteins (T antigens) contribute to tumorigenesis by inactivating tumor suppressors.

Question 187: Chemical peels using trichloroacetic acid (TCA) at 30–40% penetrate to which skin layer?

• Subcutaneous fat
• Stratum corneum only
• Deep reticular dermis
• Papillary to upper reticular dermis (Correct answer)

Correct answer: Papillary to upper reticular dermis

Medium-depth TCA peels at 30–40% penetrate through the epidermis to the papillary and upper reticular dermis, making them effective for actinic keratoses and dyspigmentation.

Question 188: Which ABCDE criterion for melanoma evaluation stands for 'Evolution'?

• The lesion has multiple colors
• The lesion has changed over time (Correct answer)
• The lesion is asymmetric
• The lesion has irregular borders

Correct answer: The lesion has changed over time

The 'E' in ABCDE stands for Evolution — any change in size, shape, color, or a new symptom such as bleeding is a warning sign of melanoma.

Question 189: A 35-year-old woman has butterfly-shaped facial erythema, photosensitivity, and a positive ANA. Which antibody is most specific for SLE?

• Anti-histone
• Anti-La (SSB)
• Anti-Ro (SSA)
• Anti-dsDNA (Correct answer)

Correct answer: Anti-dsDNA

Anti-dsDNA antibodies are highly specific for SLE and their titers often correlate with disease activity, particularly lupus nephritis.

Question 190: What wood lamp finding is characteristic of erythrasma?

• Yellow-green fluorescence
• Blue-green fluorescence
• Coral-red fluorescence (Correct answer)
• No fluorescence

Correct answer: Coral-red fluorescence

Erythrasma, caused by Corynebacterium minutissimum, produces coral-red fluorescence under Wood lamp due to porphyrins produced by the bacteria.

Question 191: The typical symptoms of this dermatologic condition include erythema, papules, and pustules, as well as follicular dilatation that affects the nose and parts of the cheeks.

• acne cosmetica
• acne pustulosa
• acne rosacea (Correct answer)
• acne vulgaris

Correct answer: acne rosacea

Acne rosacea, commonly known as rosacea, is a chronic inflammatory skin condition primarily affecting the face. Its characteristic symptoms include persistent facial redness (erythema), small red bumps (papules), pus-filled lesions (pustules), and visible blood vessels, often with follicular dilatation, particularly on the nose and cheeks. Unlike acne vulgaris, it typically lacks comedones (blackheads/whiteheads) and is more common in adults.

Question 192: Which phototherapy modality delivers narrowband ultraviolet B (NB-UVB) radiation at approximately 311–313 nm?

• Broadband UVB
• Excimer laser
• Narrowband UVB lamp (Correct answer)
• PUVA (psoralen + UVA)

Correct answer: Narrowband UVB lamp

Narrowband UVB phototherapy uses a fluorescent lamp that emits UVB radiation at the therapeutic peak of 311–313 nm, which is more effective and safer than broadband UVB.

Question 193: Which term describes the benign, dome-shaped, skin-colored papule that undergoes central umbilication and spontaneous resolution, caused by a poxvirus?

• Sebaceous hyperplasia
• Molluscum contagiosum (Correct answer)
• Milia
• Verruca vulgaris

Correct answer: Molluscum contagiosum

Molluscum contagiosum is caused by a poxvirus and presents as umbilicated papules that typically self-resolve within months to years.

Question 194: What is the name of a chronic dermatitis in people with a history of allergies that has no recognized cause?

• stasis dermatitis
• atopic dermatitis (Correct answer)
• actinic dermatitis
• seborrheic dermatitis

Correct answer: atopic dermatitis

Atopic dermatitis, also known as eczema, is a chronic inflammatory skin condition characterized by dry, intensely itchy, and inflamed skin. It often begins in childhood and is strongly associated with a personal or family history of allergies, asthma, or hay fever, forming part of the 'atopic triad.' While its exact cause is unknown, it involves a complex interplay of genetic, environmental, and immunological factors.

Question 195: Which skin sign—yellowing of the sclerae and skin—most commonly indicates which underlying metabolic process?

• Lipid deposition in xanthomatosis
• Elevated serum carotenoids from diet
• Iron deposition in hemochromatosis
• Elevated serum bilirubin from hepatic or hemolytic disease (Correct answer)

Correct answer: Elevated serum bilirubin from hepatic or hemolytic disease

True jaundice with scleral icterus reflects hyperbilirubinemia (>2–3 mg/dL) from liver disease or hemolysis, not dietary carotenoids.

Question 196: Which histochemical stain is most useful for identifying amyloid deposits in the skin, and what is its characteristic finding under polarized light?

• Alcian blue showing blue mucin deposits
• PAS stain showing magenta coloration
• Masson trichrome showing green collagen
• Congo red stain showing apple-green birefringence (Correct answer)

Correct answer: Congo red stain showing apple-green birefringence

Congo red staining with apple-green birefringence under polarized light is the gold standard for identifying amyloid deposits in skin and other tissues.

Question 197: What is the mechanism by which UV radiation causes DNA damage leading to skin cancer?

• Direct strand breaks in double-stranded DNA
• Formation of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts in DNA (Correct answer)
• Deamination of cytosine to uracil
• Generation of reactive oxygen species only

Correct answer: Formation of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts in DNA

UVB radiation causes direct DNA damage by inducing formation of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts between adjacent pyrimidine bases, causing characteristic C→T mutations.

Question 198: Dermatofibrosarcoma protuberans (DFSP) is characterized by which genetic translocation?

• t(9;22) Philadelphia chromosome
• t(17;22) resulting in COL1A1-PDGFB fusion gene (Correct answer)
• t(14;18) BCL2-IGH fusion
• t(11;22) creating EWS-FLI1 fusion

Correct answer: t(17;22) resulting in COL1A1-PDGFB fusion gene

DFSP carries a translocation t(17;22) fusing COL1A1 and PDGFB, resulting in constitutive PDGF receptor activation, which is also the rationale for treating with imatinib (Gleevec).

Question 199: Which type of melanoma is most commonly found on the palms, soles, and nail beds?

• Nodular melanoma
• Acral lentiginous melanoma (Correct answer)
• Lentigo maligna melanoma
• Superficial spreading melanoma

Correct answer: Acral lentiginous melanoma

Acral lentiginous melanoma is the most common melanoma subtype in darker-skinned individuals and arises on acral surfaces including palms, soles, and subungual regions.

Question 200: What dermatological tool, invented in the 1990s, allows in vivo visualization of the epidermis and dermal-epidermal junction without biopsy?

• Dermoscopy (dermatoscopy) (Correct answer)
• Confocal reflectance microscopy
• High-frequency ultrasound
• Optical coherence tomography

Correct answer: Dermoscopy (dermatoscopy)

Dermoscopy uses polarized or contact oil lens illumination to visualize subsurface skin structures, improving melanoma detection accuracy.