American Board of Dermatology (ABD) APPLIED Certification Exam — Questions and Answers

Question 1: Which vascular tumor is associated with HHV-8 and immunosuppression?

Kaposi sarcoma (Correct answer)
Cherry angioma
Pyogenic granuloma
Glomus tumor

Correct answer: Kaposi sarcoma

Kaposi sarcoma is driven by human herpesvirus 8 and is common in immunosuppressed or HIV-positive patients.

Question 2: A 60-year-old woman has a pearly papule on her nose. A shave biopsy shows nests of basaloid cells with peripheral palisading, scant cytoplasm, and a surrounding fibromyxoid stroma with retraction artifact. An immunohistochemical stain is performed. Which of the following stains would most strongly and diffusely support the diagnosis?

Cytokeratin 20 (CK20)
Melan-A
S-100
Ber-EP4 (Correct answer)

Correct answer: Ber-EP4

The clinical and histologic description is classic for basal cell carcinoma (BCC). Ber-EP4 is an antibody that recognizes the Epithelial Cell Adhesion Molecule (EpCAM) and is a highly sensitive and specific marker for BCC, staining it strongly and diffusely. It is particularly useful in distinguishing BCC from trichoepithelioma, which is typically negative or only focally positive. S-100 and Melan-A are melanocytic markers. Cytokeratin 20 is characteristically positive in Merkel cell carcinoma in a perinuclear dot-like pattern, but not in BCC.

Question 3: Kligman's formula, the gold standard for melasma treatment, consists of which combination?

Salicylic acid + niacinamide + retinol
Glycolic acid + vitamin C + broad-spectrum sunscreen alone
Azelaic acid + kojic acid + benzoyl peroxide
Tretinoin + hydroquinone + low-potency topical corticosteroid (Correct answer)

Correct answer: Tretinoin + hydroquinone + low-potency topical corticosteroid

Kligman's formula combines tretinoin (enhances penetration and turnover), hydroquinone (inhibits tyrosinase), and a low-potency corticosteroid (reduces irritation), targeting melasma through multiple mechanisms.

Question 4: A dermatopathology specimen reveals a dermal spindle cell neoplasm. The tumor cells are positive for CD34 but negative for Factor XIIIa and S-100. The clinical presentation was a rapidly growing nodule on the trunk of an adult. Which of the following entities is most consistent with these findings?

Atypical Fibroxanthoma (AFX)
Dermatofibroma (Benign Fibrous Histiocytoma)
Neurofibroma
Dermatofibrosarcoma Protuberans (DFSP) (Correct answer)

Correct answer: Dermatofibrosarcoma Protuberans (DFSP)

Dermatofibrosarcoma protuberans (DFSP) is a spindle cell neoplasm that characteristically shows strong and diffuse positivity for CD34. In contrast, dermatofibromas are typically positive for Factor XIIIa and negative for CD34 (though some variants can be positive). Neurofibromas are S-100 positive. Atypical fibroxanthoma is a diagnosis of exclusion and is typically negative for CD34, S-100, and cytokeratins, but often positive for CD10.

Question 5: A young adult presents with a single large 'herald patch' followed by a christmas-tree distribution of scaly macules. What is the diagnosis?

Nummular eczema
Guttate psoriasis
Secondary syphilis
Pityriasis rosea (Correct answer)

Correct answer: Pityriasis rosea

A herald patch preceding a christmas-tree pattern of oval scaly lesions along skin cleavage lines is diagnostic of pityriasis rosea.

Question 6: Which SPF value blocks approximately 97% of UVB radiation?

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

Correct answer: SPF 30

SPF 30 blocks approximately 97% of UVB radiation; SPF 15 blocks 93%, SPF 50 blocks 98%, and SPF 100 blocks 99%, showing diminishing returns at higher values.

Question 7: Aggressive histologic subtypes such as morpheaform BCC warrant Mohs because they?

Never recur
Have poorly defined subclinical extension (Correct answer)
Are always benign
Only occur in children

Correct answer: Have poorly defined subclinical extension

Morpheaform BCC has ill-defined margins with subclinical spread, favoring margin-controlled Mohs surgery.

Question 8: A neonate has a linear array of vesicles along Blaschko's lines followed by verrucous streaks. This first-stage finding suggests which X-linked disorder?

Goltz syndrome
Hypomelanosis of Ito
Epidermolysis bullosa
Incontinentia pigmenti (Correct answer)

Correct answer: Incontinentia pigmenti

Incontinentia pigmenti presents with vesicular, verrucous, hyperpigmented, and atrophic stages along Blaschko's lines in females.

Question 9: Pautrier microabscesses (intraepidermal collections of atypical lymphocytes) are a diagnostic feature of which condition?

Mycosis fungoides (Correct answer)
Spongiotic dermatitis
Psoriasis
Lichen simplex chronicus

Correct answer: Mycosis fungoides

Pautrier microabscesses are clusters of atypical T-cells in the epidermis seen in mycosis fungoides (cutaneous T-cell lymphoma).

Question 10: Which histologic parameter is the most important prognostic factor in cutaneous melanoma?

Clark level
Mitotic rate alone
Lesion diameter
Breslow thickness (Correct answer)

Correct answer: Breslow thickness

Breslow depth (tumor thickness in mm) is the strongest predictor of melanoma prognosis and staging.

Question 11: A 68-year-old male with a history of a renal transplant presents with a 2.5 cm, poorly demarcated, recurrent basal cell carcinoma on his left temple. The biopsy shows an infiltrative growth pattern. According to the Appropriate Use Criteria, which of the following is the most appropriate next step in management?

Radiation therapy
Excisional surgery with 5-mm margins
Mohs micrographic surgery (Correct answer)
Topical imiquimod

Correct answer: Mohs micrographic surgery

Mohs micrographic surgery is the standard of care for high-risk basal cell carcinomas. This patient has multiple high-risk features including a large size (>1 cm on the face), location in a high-risk anatomic area (temple), recurrent tumor, immunosuppression, and an aggressive histologic subtype (infiltrative). Mohs surgery offers the highest cure rate while maximizing tissue conservation, which is critical in this cosmetically sensitive area.

Question 12: A child presents with discrete pink papules with a central white 'herald patch' followed by a Christmas-tree distribution of oval scaly macules. What is the diagnosis?

Pityriasis rosea (Correct answer)
Tinea corporis
Guttate psoriasis
Nummular eczema

Correct answer: Pityriasis rosea

Pityriasis rosea begins with a herald patch followed by a Christmas-tree pattern of lesions along skin cleavage lines.

Question 13: Nail pitting, oil-drop discoloration, and onycholysis in a psoriasis patient raise concern for which associated condition?

Tinea unguium only
Lichen striatus
Psoriatic arthritis (Correct answer)
Contact dermatitis

Correct answer: Psoriatic arthritis

Nail involvement in psoriasis correlates strongly with concurrent or future psoriatic arthritis.

Question 14: A hedgehog pathway inhibitor such as vismodegib is FDA-approved for which malignancy?

Merkel cell carcinoma
Cutaneous T-cell lymphoma
Locally advanced or metastatic basal cell carcinoma (Correct answer)
Metastatic melanoma

Correct answer: Locally advanced or metastatic basal cell carcinoma

Vismodegib targets the SMO component of the hedgehog pathway driving advanced BCC.

Question 15: When evaluating melanoma, which histologic feature is the single most important prognostic factor in the AJCC staging system?

Breslow depth (tumor thickness) (Correct answer)
Clark level
Lesion diameter
Presence of pigment

Correct answer: Breslow depth (tumor thickness)

Breslow thickness (depth in millimeters) is the most important primary-tumor prognostic factor for cutaneous melanoma.

Question 16: Angiosarcoma of the scalp in elderly patients typically presents as:

A stable pearly papule
A scaly hyperkeratotic patch
A bruise-like violaceous plaque that enlarges (Correct answer)
A pigmented macule

Correct answer: A bruise-like violaceous plaque that enlarges

Cutaneous angiosarcoma often mimics a persistent, enlarging bruise on the scalp or face of older adults.

Question 17: A child with tuberous sclerosis is examined for cutaneous findings. Which lesion is a well-recognized diagnostic criterion?

Port-wine stain
Ash-leaf macules (Correct answer)
Aplasia cutis
Café-au-lait macules

Correct answer: Ash-leaf macules

Hypopigmented ash-leaf macules are an early cutaneous marker of tuberous sclerosis.

Question 18: When is it appropriate for a dermatologist to prescribe isotretinoin under iPLEDGE?

For any patient who requests it immediately
Only after meeting all iPLEDGE registration and pregnancy-testing requirements (Correct answer)
Only for male patients regardless of program
Without any registration

Correct answer: Only after meeting all iPLEDGE registration and pregnancy-testing requirements

iPLEDGE mandates registration and pregnancy prevention protocols before prescribing.

Question 19: A tender, well-demarcated, raised, bright red facial plaque with a sharp border is characteristic of:

Rosacea
Contact dermatitis
Erysipelas (Correct answer)
Cellulitis

Correct answer: Erysipelas

Erysipelas is a superficial streptococcal infection with a raised, sharply demarcated border.

Question 20: What is the main ethical responsibility during a skin examination?

Prescribe without explanation
Obtain informed consent (Correct answer)
Take photos without informing the patient
Skip documentation for speed

Correct answer: Obtain informed consent

Obtaining informed consent is an essential ethical and legal responsibility before any medical examination or procedure, including a skin examination. It ensures that the patient understands the nature of the examination, its purpose, potential risks, and benefits, and voluntarily agrees to proceed. This respects patient autonomy and builds trust.

Question 21: A toddler presents with an annular scaly plaque with central clearing and a raised active border. KOH prep confirms hyphae. First-line treatment for tinea corporis in children is?

Oral griseofulvin
Oral fluconazole
Topical corticosteroid
Topical terbinafine (Correct answer)

Correct answer: Topical terbinafine

Localized tinea corporis in children is treated with a topical antifungal such as terbinafine.

Question 22: Which oral antifungal carries the highest risk of hepatotoxicity and drug interactions via CYP3A4?

Griseofulvin
Nystatin
Terbinafine
Ketoconazole (Correct answer)

Correct answer: Ketoconazole

Oral ketoconazole is a strong CYP3A4 inhibitor with significant hepatotoxicity risk.

Question 23: A child presents with a port-wine stain in the V1 trigeminal distribution. Which syndrome should be evaluated for with neuroimaging?

Sturge-Weber syndrome (Correct answer)
Klippel-Trenaunay syndrome
Proteus syndrome
PHACE syndrome

Correct answer: Sturge-Weber syndrome

A V1-distribution port-wine stain raises concern for Sturge-Weber syndrome with leptomeningeal angiomatosis and glaucoma.

Question 24: A skin biopsy shows a 'sawtooth' pattern of the rete ridges with a band-like lymphocytic infiltrate at the dermoepidermal junction. What is the diagnosis?

Discoid lupus erythematosus
Psoriasis
Lichen planus (Correct answer)
Pityriasis rosea

Correct answer: Lichen planus

Sawtooth rete ridges with a band-like (lichenoid) interface lymphocytic infiltrate are classic for lichen planus.

Question 25: Which immunostain shows a characteristic paranuclear dot pattern in Merkel cell carcinoma?

TTF-1
CD45
S100
CK20 (Correct answer)

Correct answer: CK20

CK20 typically shows perinuclear dot-like staining while TTF-1 is negative, helping distinguish MCC from metastatic small cell lung cancer.

Question 26: A Fite (acid-fast) stain would be most useful in diagnosing which cutaneous infection?

Candidiasis
Syphilis
Leprosy (Hansen disease) (Correct answer)
Herpes simplex

Correct answer: Leprosy (Hansen disease)

The Fite stain is a modified acid-fast stain optimal for demonstrating Mycobacterium leprae.

Question 27: Pachyonychia congenita type 1 (Jadassohn-Lewandowsky syndrome) is caused by mutations in which keratins?

KRT6A or KRT16 (Correct answer)
KRT1 or KRT10
KRT5 or KRT14
KRT6B or KRT17

Correct answer: KRT6A or KRT16

PC type 1 is caused by mutations in KRT6A or KRT16, presenting with wedge-shaped thickened nails, palmoplantar keratoderma, and oral leukokeratosis.

Question 28: A 65-year-old man has a biopsy of a plaque on his buttock. Histopathology reveals a band-like dermal infiltrate of atypical lymphocytes with cerebriform nuclei showing prominent epidermotropism and forming Pautrier's microabscesses. Which immunophenotype is most characteristic of the neoplastic cells in this condition?

CD20+, CD79a+, CD5-
CD3+, CD4+, CD8- (Correct answer)
CD56+, CD3-, Synaptophysin+
CD30+, CD15-, ALK-

Correct answer: CD3+, CD4+, CD8-

The clinical and histopathologic findings are classic for Mycosis Fungoides, the most common type of cutaneous T-cell lymphoma (CTCL). The neoplastic cells are typically mature, skin-homing helper T-cells. Their characteristic immunophenotype is CD3+ (pan T-cell marker), CD4+ (helper T-cell marker), and CD8- (cytotoxic T-cell marker). Loss of pan-T-cell antigens like CD7 is also common.

Question 29: An infant presents with a rapidly enlarging strawberry-red plaque on the face. Which complication warrants urgent systemic beta-blocker therapy?

Slow spontaneous involution
Periocular location threatening the visual axis (Correct answer)
Isolated truncal location
Cosmetic disfigurement only

Correct answer: Periocular location threatening the visual axis

Periocular infantile hemangiomas obstructing the visual axis risk amblyopia and require prompt propranolol treatment.

Question 30: Sturge-Weber syndrome and isolated port-wine stains are associated with somatic mosaic mutations in which gene?

AKT1
GNAQ (Correct answer)
GNAS
RASA1

Correct answer: GNAQ

Somatic activating GNAQ (p.R183Q) mutations underlie both Sturge-Weber syndrome and nonsyndromic port-wine stains.

Question 31: An aquarium enthusiast develops a papule on his right index finger two weeks after sustaining a small cut while cleaning his fish tank. Over the next month, several more erythematous nodules appear in a linear fashion ascending up his forearm. This specific clinical pattern is best described as:

Tuberculoid spread
Erysipeloid spread
Sporotrichoid spread (Correct answer)
Herpetiform spread

Correct answer: Sporotrichoid spread

The patient's history of a fish tank injury followed by the development of nodules ascending along the lymphatic drainage is a classic presentation for Mycobacterium marinum infection, also known as 'fish tank granuloma'. This linear arrangement of nodules along lymphatic channels is termed a sporotrichoid pattern or spread, named after its resemblance to the presentation of sporotrichosis.

Question 32: The HLA-Cw6 allele shows the strongest genetic association with which dermatologic disease?

Bullous pemphigoid
Vitiligo
Psoriasis (Correct answer)
Alopecia areata

Correct answer: Psoriasis

HLA-Cw6 is the principal susceptibility allele for early-onset psoriasis.

Question 33: A dermatologist maintaining board certification demonstrates lifelong learning primarily through:

Attending unrelated conferences only
No further education after residency
Ongoing CME and periodic knowledge assessment (Correct answer)
A single exam taken decades ago

Correct answer: Ongoing CME and periodic knowledge assessment

Continuing certification requires ongoing CME and periodic assessments.

Question 34: Periungual fibromas (Koenen tumors) around the nails are a diagnostic feature of which condition?

Cowden syndrome
Gardner syndrome
Neurofibromatosis type 2
Tuberous sclerosis complex (Correct answer)

Correct answer: Tuberous sclerosis complex

Koenen tumors are periungual/subungual fibromas that typically appear in adolescence in tuberous sclerosis.

Question 35: An infant develops widespread flaccid bullae and superficial desquamation with a positive Nikolsky sign but spares mucous membranes. What is the diagnosis?

Bullous pemphigoid
Stevens-Johnson syndrome
Toxic epidermal necrolysis
Staphylococcal scalded skin syndrome (Correct answer)

Correct answer: Staphylococcal scalded skin syndrome

SSSS is caused by staphylococcal exfoliative toxins, cleaves the granular layer, and characteristically spares mucosa.

Question 36: Immunofluorescence showing a linear IgG and C3 deposition along the basement membrane zone is characteristic of which blistering disease?

Pemphigus vulgaris
Dermatitis herpetiformis
Lichen planus
Bullous pemphigoid (Correct answer)

Correct answer: Bullous pemphigoid

Bullous pemphigoid shows linear IgG and C3 at the dermoepidermal basement membrane zone.

Question 37: What is the maximum safe dose of lidocaine with epinephrine per kilogram?

7 mg/kg (Correct answer)
3 mg/kg
1 mg/kg
15 mg/kg

Correct answer: 7 mg/kg

Lidocaine with epinephrine has a maximum safe dose of approximately 7 mg/kg.

Question 38: The Fitzpatrick skin phototype classification system categorizes human skin into how many phototypes?

6 (Correct answer)
5
8
4

Correct answer: 6

The Fitzpatrick scale classifies skin into 6 phototypes (I-VI) based on constitutive pigmentation and the skin's response to UV exposure (burning versus tanning).

Question 39: Which cytokine is considered central to the pathogenesis of psoriasis by acting on T cells to promote their differentiation into and maintenance of the Th17 phenotype?

Interleukin-4 (IL-4)
Transforming growth factor-β (TGF-β)
Interleukin-10 (IL-10)
Interleukin-23 (IL-23) (Correct answer)

Correct answer: Interleukin-23 (IL-23)

Interleukin-23 (IL-23), produced primarily by dendritic cells, is a key regulatory cytokine that drives the pathogenesis of psoriasis. It is crucial for the survival, expansion, and pathogenic function of Th17 cells, which in turn produce effector cytokines like IL-17 and IL-22 that cause keratinocyte hyperproliferation and inflammation.

Question 40: A 10-year-old presents with well-demarcated erythematous plaques with silvery scale on the elbows and knees, plus pinpoint nail pitting. What is the diagnosis?

Psoriasis vulgaris (Correct answer)
Seborrheic dermatitis
Atopic dermatitis
Lichen planus

Correct answer: Psoriasis vulgaris

Silvery-scaled plaques on extensor surfaces with nail pitting are characteristic of psoriasis.

Question 41: A well-appearing 2-week-old has small yellow-white papules on the nose that resolve without treatment. What are these lesions?

Milia (Correct answer)
Neonatal acne
Sebaceous hyperplasia
Erythema toxicum neonatorum

Correct answer: Milia

Milia are tiny keratin-filled cysts common on the neonatal face that resolve spontaneously.

Question 42: A dermatologist should decline to treat a family member for a serious condition primarily because:

Objectivity and proper documentation may be compromised (Correct answer)
It is always illegal
Family members never need care
Insurance forbids it universally

Correct answer: Objectivity and proper documentation may be compromised

Treating close family can impair objectivity and appropriate record-keeping.

Question 43: Which stain best highlights the eccrine ductal differentiation of microcystic adnexal carcinoma versus a benign syringoma?

Melan-A
Depth of infiltration and perineural invasion on excision (Correct answer)
Mucicarmine positivity
Immunostains alone reliably distinguish them

Correct answer: Depth of infiltration and perineural invasion on excision

MAC is distinguished from syringoma largely by its deep infiltrative growth and perineural invasion rather than by a single stain.

Question 44: An 8-year-old child is evaluated for multiple hypopigmented macules on the trunk that have been present since infancy. The examination reveals three ash-leaf spots, facial angiofibromas, and a shagreen patch on the lower back. This constellation of findings is most characteristic of which genetic disorder?

Epidermolysis bullosa
Neurofibromatosis type 1
Tuberous sclerosis complex (Correct answer)
Incontinentia pigmenti

Correct answer: Tuberous sclerosis complex

The combination of hypopigmented macules (ash-leaf spots), facial angiofibromas, and a shagreen patch are major cutaneous features highly characteristic of Tuberous Sclerosis Complex (TSC). Neurofibromatosis type 1 presents with cafe-au-lait macules and neurofibromas, while the other options have distinctly different cutaneous manifestations.

Question 45: Cryosurgery destroys tissue primarily through?

Heat coagulation
Chemical cautery
Radiation
Intracellular ice crystal formation (Correct answer)

Correct answer: Intracellular ice crystal formation

Rapid freezing causes intracellular ice crystals that rupture cell membranes.

Question 46: A 45-year-old presents with a well-demarcated, salmon-colored plaque with silvery scale on the extensor elbow. Pinpoint bleeding appears when scale is removed. What is this sign called?

Darier sign
Auspitz sign (Correct answer)
Nikolsky sign
Koebner sign

Correct answer: Auspitz sign

The Auspitz sign is pinpoint bleeding after removal of psoriatic scale, reflecting dilated dermal capillaries.

Question 47: Which combination of features best differentiates dermal melanocytosis (Mongolian spot) from non-accidental trauma (bruising) in an infant?

All of the above (Correct answer)
Presence at birth
Location on the lumbosacral area only
Blue-gray color stable over days without color evolution or associated edema

Correct answer: All of the above

Mongolian spots are congenital (present at birth), located characteristically on the lumbosacral region, and show stable blue-gray color without the sequential color change (purple→green→yellow) or swelling that accompanies bruising.

Question 48: Why is it important to read peer-reviewed dermatology journals?

They offer evidence-based clinical updates. (Correct answer)
They replace patient interaction.
They are required reading for residency.
They contain fictional stories.

Correct answer: They offer evidence-based clinical updates.

Peer-reviewed dermatology journals are critical resources for dermatologists because they publish research findings, clinical trials, and reviews that have been rigorously evaluated by experts in the field. This ensures that the information is evidence-based, allowing practitioners to stay current with the latest advancements, best practices, and treatment guidelines, ultimately improving patient care.

Question 49: Terbinafine is most effective against which type of infection?

Herpes simplex
Bacterial folliculitis
Candidiasis
Dermatophyte onychomycosis (Correct answer)

Correct answer: Dermatophyte onychomycosis

Terbinafine, an allylamine, is first-line oral therapy for dermatophyte nail infections.

Question 50: Trichilemmomas and oral papillomas with increased breast and thyroid cancer risk characterize which PTEN-related syndrome?

Birt-Hogg-Dubé syndrome
Muir-Torre syndrome
Cowden syndrome (Correct answer)
Gorlin syndrome

Correct answer: Cowden syndrome

Cowden syndrome (PTEN mutation) presents with facial trichilemmomas, oral cobblestoning, and risk of breast and thyroid cancers.

Question 51: A patient requests that a dermatologist not disclose a melanoma diagnosis to their family members who are also your patients. What is the most appropriate action?

Post the diagnosis in a shared chart note visible to family
Immediately warn all related patients of hereditary risk
Honor patient confidentiality and do not disclose to family (Correct answer)
Disclose only to the spouse

Correct answer: Honor patient confidentiality and do not disclose to family

Patient confidentiality must be maintained unless the patient consents to disclosure.

Question 52: Histology of lichen planus classically shows a band-like lymphocytic infiltrate at the dermoepidermal junction with what saw-tooth change?

Subepidermal blister
Follicular plugging only
Suprabasal acantholysis
Sawtooth acanthosis of the rete ridges (Correct answer)

Correct answer: Sawtooth acanthosis of the rete ridges

Lichen planus shows a dense band-like (lichenoid) infiltrate with sawtooth rete ridges and hypergranulosis.

Question 53: Guttate psoriasis in a child or young adult is most classically triggered by which preceding infection?

Herpes simplex
Candida intertrigo
Streptococcal pharyngitis (Correct answer)
Molluscum contagiosum

Correct answer: Streptococcal pharyngitis

Guttate psoriasis frequently follows a group A streptococcal throat infection.

Question 54: A 58-year-old male with extensive plaque psoriasis is being managed with weekly low-dose methotrexate. To mitigate the risk of hepatotoxicity, which of the following is the most crucial long-term monitoring strategy according to consensus guidelines?

Annual liver biopsy regardless of other findings
Weekly complete blood count with differential
Monthly assessment of serum aminotransferases and periodic procollagen III aminopeptide (PІІІNP) levels (Correct answer)
Bi-annual abdominal ultrasound to assess for hepatic steatosis

Correct answer: Monthly assessment of serum aminotransferases and periodic procollagen III aminopeptide (PІІІNP) levels

Consensus guidelines for monitoring methotrexate-induced hepatotoxicity in psoriasis focus on regular laboratory surveillance. This includes frequent monitoring of liver transaminases (e.g., ALT) and, in many guidelines, periodic assessment of PIIINP, a marker of fibrogenesis. Liver biopsy is reserved for patients with persistently elevated liver enzymes or PIIINP levels, or those with multiple risk factors for liver disease. Abdominal ultrasound is not a primary screening tool for fibrosis. While a weekly CBC is essential for monitoring for myelosuppression, it does not assess for hepatotoxicity.

Question 55: A linear vesicular eruption on an exposed forearm after a hike is most characteristic of contact dermatitis from what?

Fragrance in lotion
Urushiol (poison ivy/oak) (Correct answer)
Latex gloves
Nickel jewelry

Correct answer: Urushiol (poison ivy/oak)

Linear streaks of vesicles from plant brush-past are classic for urushiol-induced (Rhus) contact dermatitis.

Question 56: Which sunscreen ingredient provides broad-spectrum protection by physically reflecting UV radiation?

Octinoxate
Oxybenzone
Zinc oxide (Correct answer)
Avobenzone

Correct answer: Zinc oxide

Zinc oxide is a physical (mineral) blocker that reflects and scatters both UVA and UVB radiation.

Question 57: A biopsy of a verrucous plaque from the lower leg of an elderly diabetic patient shows pseudoepitheliomatous hyperplasia, a mixed inflammatory infiltrate with neutrophils forming microabscesses, and small, round, copper-colored sclerotic bodies, some of which are undergoing septation. What is the most likely diagnosis?

Chromoblastomycosis (Correct answer)
Blastomycosis
Histoplasmosis
Coccidioidomycosis

Correct answer: Chromoblastomycosis

The presence of pseudoepitheliomatous hyperplasia with neutrophilic abscesses is a common reaction pattern to deep fungal infections. The key diagnostic finding described is the 'copper penny' or sclerotic body (also known as a Medlar body), which is pathognomonic for chromoblastomycosis. These are pigmented, thick-walled, round fungal forms that may show internal septations. Blastomycosis shows broad-based budding yeast, coccidioidomycosis presents as large spherules containing endospores, and histoplasmosis is characterized by small intracellular yeasts within macrophages.

Question 58: Corps ronds and grains, reflecting abnormal keratinization with acantholytic dyskeratosis, are seen in which disorder?

Warty dyskeratoma only
Bowen disease
Darier disease (Correct answer)
Pemphigus vulgaris

Correct answer: Darier disease

Corps ronds and grains are the characteristic dyskeratotic cells of Darier disease (keratosis follicularis).

Question 59: Which topical agent is first-line treatment for scabies?

Clotrimazole
Permethrin 5% cream (Correct answer)
Hydrocortisone
Mupirocin

Correct answer: Permethrin 5% cream

Permethrin 5% cream is the standard first-line scabicide.

Question 60: Which lesion is considered pre-malignant?

Actinic keratosis (Correct answer)
Seborrheic keratosis
Cherry angioma
Skin tag

Correct answer: Actinic keratosis

Actinic keratosis (AK) is considered a pre-malignant lesion, meaning it has the potential to develop into skin cancer. These rough, scaly patches typically appear on sun-exposed areas and are caused by chronic ultraviolet radiation damage. If left untreated, AKs can progress to invasive squamous cell carcinoma, making early detection and treatment crucial for prevention.

Question 61: A child with atopic dermatitis develops punched-out monomorphic vesicles and erosions over the eczematous areas with fever. What is the diagnosis?

Eczema herpeticum (Correct answer)
Contact dermatitis
Impetigo
Molluscum contagiosum

Correct answer: Eczema herpeticum

Eczema herpeticum is a disseminated HSV infection over eczematous skin requiring systemic acyclovir.

Question 62: A child develops sharply demarcated perianal erythema with painful defecation and no systemic symptoms. What is the likely diagnosis?

Candidal dermatitis
Irritant dermatitis
Pinworm infection
Perianal streptococcal dermatitis (Correct answer)

Correct answer: Perianal streptococcal dermatitis

Perianal streptococcal dermatitis presents as bright, well-demarcated perianal erythema caused by group A Streptococcus.

Question 63: Which stain is most useful for highlighting mucin deposition in the dermis, as seen in lupus erythematosus?

PAS with diastase
Colloidal iron (or Alcian blue) (Correct answer)
Congo red
Fite stain

Correct answer: Colloidal iron (or Alcian blue)

Colloidal iron and Alcian blue stain acid mucopolysaccharides, highlighting dermal mucin.

Question 64: Flame figures (eosinophilic material coating collagen) are the histologic hallmark of which condition?

Sweet syndrome
Granuloma annulare
Erythema nodosum
Wells syndrome (eosinophilic cellulitis) (Correct answer)

Correct answer: Wells syndrome (eosinophilic cellulitis)

Flame figures — degranulated eosinophil major basic protein on collagen — are characteristic of Wells syndrome.

Question 65: A well-appearing neonate develops erythematous macules with central pustules on the trunk in the first days of life; a Wright stain shows eosinophils. What is the diagnosis?

Staphylococcal pustulosis
Erythema toxicum neonatorum (Correct answer)
Neonatal herpes
Transient neonatal pustular melanosis

Correct answer: Erythema toxicum neonatorum

Erythema toxicum neonatorum is a benign self-limited eruption with eosinophils on smear.

Question 66: Hydroa vacciniforme is associated with latent infection with which virus?

Human herpesvirus 6 (HHV-6)
Herpes simplex virus type 1
Epstein-Barr virus (EBV) (Correct answer)
Cytomegalovirus (CMV)

Correct answer: Epstein-Barr virus (EBV)

Hydroa vacciniforme and hydroa vacciniforme-like lymphoproliferative disorder are strongly associated with Epstein-Barr virus (EBV) infection.

Question 67: Which cytokine, targeted by ustekinumab (with IL-12), is critical for Th17 differentiation in psoriasis?

IL-8
IL-2
IL-6
IL-23 (Correct answer)

Correct answer: IL-23

IL-23 maintains Th17 cells and is co-targeted by ustekinumab via the shared p40 subunit.

Question 68: A 6-year-old develops a solitary tan macule with a 'coast of Maine' irregular border. This finding is most associated with which condition?

Tuberous sclerosis
Neurofibromatosis type 1
McCune-Albright syndrome (Correct answer)
Legius syndrome

Correct answer: McCune-Albright syndrome

Large café-au-lait macules with irregular 'coast of Maine' borders are characteristic of McCune-Albright syndrome.

Question 69: An itchy child has burrows in the finger webs and family members with similar pruritus. What is the treatment of choice?

Topical corticosteroid
Permethrin 5% cream (Correct answer)
Oral acyclovir
Topical mupirocin

Correct answer: Permethrin 5% cream

Scabies is treated with topical permethrin 5%, with treatment of household contacts.

Question 70: Allergic contact dermatitis to nickel is an example of which Gell and Coombs hypersensitivity type?

Type III
Type II
Type I
Type IV (Correct answer)

Correct answer: Type IV

Allergic contact dermatitis is a type IV, T-cell-mediated delayed hypersensitivity reaction.

Question 71: A 9-month-old infant presents with a persistent, scaly, crusted rash in the scalp and axillae that has been unresponsive to topical corticosteroids and antifungals. Examination reveals yellowish-brown scaly papules with scattered petechiae within the plaques. Which diagnosis should be strongly considered?

Langerhans cell histiocytosis (Correct answer)
Acrodermatitis enteropathica
Scabies
Psoriasis

Correct answer: Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) in infants can mimic severe seborrheic dermatitis, particularly in the scalp and intertriginous areas. The presence of petechiae or purpura within the lesions and the failure to respond to standard therapies are critical red flags for LCH. A skin biopsy is required for definitive diagnosis.

Question 72: Nicotinamide (vitamin B3) supplementation has been shown to do what in high-risk patients?

Eliminate the need for sun protection
Reduce the rate of new keratinocyte carcinomas and actinic keratoses (Correct answer)
Treat metastatic BCC
Cure established melanoma

Correct answer: Reduce the rate of new keratinocyte carcinomas and actinic keratoses

Oral nicotinamide reduces incidence of new nonmelanoma skin cancers and actinic keratoses in high-risk patients.

Question 73: For a well-defined primary basal cell carcinoma under 2 cm on the trunk, recommended surgical margin is?

2 cm
1 cm
1 mm
4 mm (Correct answer)

Correct answer: 4 mm

A 4 mm margin achieves high cure rates for small, well-defined primary BCCs.

Question 74: Which syndrome predisposes to multiple basal cell carcinomas, odontogenic keratocysts, and palmar pits?

Cowden syndrome
Xeroderma pigmentosum
Gorlin (nevoid basal cell carcinoma) syndrome (Correct answer)
Muir-Torre syndrome

Correct answer: Gorlin (nevoid basal cell carcinoma) syndrome

Gorlin syndrome results from PTCH1 mutations causing numerous BCCs, jaw cysts, and palmar/plantar pits.

Question 75: Mohs micrographic surgery offers its advantage primarily through:

Wider standard excision margins
Complete peripheral and deep margin assessment of 100% of the margin (Correct answer)
Frozen section of vertical bread-loaf margins
Radiation to the tumor bed

Correct answer: Complete peripheral and deep margin assessment of 100% of the margin

Mohs evaluates essentially the entire surgical margin, maximizing cure while sparing normal tissue.

Question 76: Curettage is often performed before electrodesiccation because tumor tissue is?

Softer and more friable than normal dermis (Correct answer)
Identical in texture
Harder than surrounding dermis
Fully encapsulated

Correct answer: Softer and more friable than normal dermis

Friable tumor tissue curettes away more easily than the firmer surrounding normal dermis.

Question 77: Lichen planopilaris is a variant of lichen planus that leads to which outcome on the scalp?

Seborrheic dermatitis
Non-scarring diffuse shedding
Reversible telogen effluvium
Scarring (cicatricial) alopecia (Correct answer)

Correct answer: Scarring (cicatricial) alopecia

Lichen planopilaris causes permanent scarring alopecia by destroying hair follicle stem cells.

Question 78: A dermal tumor of small round blue cells shows a paranuclear dot-like CK20 immunostaining pattern. What is the diagnosis?

Small cell melanoma
Basal cell carcinoma
Merkel cell carcinoma (Correct answer)
Lymphoma

Correct answer: Merkel cell carcinoma

Perinuclear dot-like CK20 positivity is characteristic of Merkel cell carcinoma, a neuroendocrine tumor.

Question 79: For melanoma, sentinel lymph node biopsy is generally recommended starting at what Breslow thickness (with no other high-risk features)?

1.0 mm
0.5 mm
2.0 mm
0.8 mm (Correct answer)

Correct answer: 0.8 mm

SLNB is considered for melanomas ≥0.8 mm or thinner lesions with ulceration.

Question 80: UVA radiation (320-400nm) primarily penetrates to which level of the skin?

Epidermis only
Subcutaneous fat
Dermis (Correct answer)
Stratum corneum only

Correct answer: Dermis

UVA radiation penetrates deeply into the dermis, reaching dermal fibroblasts and blood vessels, and is the primary driver of photoaging and tanning through oxidative mechanisms.

Question 81: Interferon-gamma released by Th1 cells primarily activates which cell to enhance intracellular pathogen killing?

Macrophage (Correct answer)
Basophil
Mast cell
Plasma cell

Correct answer: Macrophage

IFN-gamma is the key macrophage-activating cytokine of the Th1 response.

Question 82: A 45-year-old man presents with a slowly growing, firm, flesh-colored nodule on his scalp. Histopathologic examination reveals a well-circumscribed, non-encapsulated dermal neoplasm composed of nests and cords of basaloid cells. The nests exhibit peripheral palisading and are embedded in a prominent, hyalinized, eosinophilic stroma. Notably, there are two distinct populations of basaloid cells and small duct-like structures. Which of the following is the most likely diagnosis?

Spiradenoma
Trichoepithelioma
Cylindroma (Correct answer)
Basal cell carcinoma

Correct answer: Cylindroma

The histopathologic features described, particularly the 'jigsaw' or 'mosaic' pattern of basaloid cell nests within a hyalinized stroma, are classic for a cylindroma. The presence of two cell populations and ductal differentiation are also characteristic features. While trichoepithelioma and basal cell carcinoma are in the differential for basaloid neoplasms, they do not typically exhibit the prominent hyalinized stroma and jigsaw puzzle appearance. Spiradenomas are composed of two cell types but typically form well-defined nodules in the deep dermis or subcutis and can be painful.

Question 83: Actinic keratoses are considered precursors to which malignancy?

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

Correct answer: Squamous cell carcinoma

Actinic keratoses are premalignant lesions that may progress to squamous cell carcinoma.

Question 84: A dense dermal nodular infiltrate of neutrophils with papillary dermal edema, without vasculitis, in a febrile patient suggests which diagnosis?

Sweet syndrome (acute febrile neutrophilic dermatosis) (Correct answer)
Pyoderma gangrenosum
Cellulitis
Leukocytoclastic vasculitis

Correct answer: Sweet syndrome (acute febrile neutrophilic dermatosis)

A diffuse dermal neutrophilic infiltrate with marked papillary edema and no true vasculitis characterizes Sweet syndrome.

Question 85: A patient presents with painful vesicular lesions on the finger following contact with oral secretions. This is termed:

Erysipeloid
Paronychia
Herpetic whitlow (Correct answer)
Orf

Correct answer: Herpetic whitlow

Herpetic whitlow is an HSV infection of the finger, common in healthcare workers and children who suck their fingers.

Question 86: Direct immunofluorescence showing granular IgA deposits in the dermal papillae supports which diagnosis?

Linear IgA disease
Bullous pemphigoid
Pemphigus foliaceus
Dermatitis herpetiformis (Correct answer)

Correct answer: Dermatitis herpetiformis

Granular IgA in the dermal papillary tips is the hallmark of dermatitis herpetiformis.

Question 87: Overlying epidermal collarette with a lobular capillary proliferation and a friable rapidly growing lesion describes which entity?

Kaposi sarcoma
Glomus tumor
Angiosarcoma
Pyogenic granuloma (lobular capillary hemangioma) (Correct answer)

Correct answer: Pyogenic granuloma (lobular capillary hemangioma)

Pyogenic granuloma is a lobular capillary hemangioma, often with an epidermal collarette at the base.

Question 88: Which cutaneous finding is a recognized marker of internal malignancy?

Seborrheic keratosis
Acanthosis nigricans (Correct answer)
Cherry angioma
Dermatofibroma

Correct answer: Acanthosis nigricans

Sudden, widespread acanthosis nigricans can be a paraneoplastic sign, classically of gastric adenocarcinoma.

Question 89: A patient with a history of recurrent severe herpes simplex virus (HSV) infections is suspected of having a defect in innate immune recognition. Which of the following Toll-like receptors, located within the endosome, is most critical for recognizing viral genomic DNA and initiating an interferon response?

TLR9 (Correct answer)
TLR2
TLR4
TLR5

Correct answer: TLR9

Toll-like receptor 9 (TLR9) is an intracellular pattern recognition receptor located in the endosomal compartment. It specializes in recognizing unmethylated CpG motifs present in bacterial and viral DNA, such as that from HSV. This recognition is a key step in triggering a type I interferon response critical for antiviral immunity.

Question 90: Sézary syndrome is defined by mycosis fungoides plus which additional feature?

Nodal involvement only
Bone marrow blasts
Large-cell transformation
Erythroderma with circulating atypical T-cells (Correct answer)

Correct answer: Erythroderma with circulating atypical T-cells

Sézary syndrome is the leukemic variant of CTCL with erythroderma and clonal Sézary cells in blood.

Question 91: Idiopathic guttate hypomelanosis is best described as:

Congenital hypopigmented macules with central clearing
Autoimmune complete depigmentation in sun-exposed skin of young adults
Drug-induced melanocyte toxicity presenting on the legs
Multiple discrete small porcelain-white macules on chronically sun-exposed extremities of middle-aged and older adults due to focal melanocyte loss (Correct answer)

Correct answer: Multiple discrete small porcelain-white macules on chronically sun-exposed extremities of middle-aged and older adults due to focal melanocyte loss

Idiopathic guttate hypomelanosis presents as multiple small, well-demarcated white macules on chronically sun-damaged extremities (shins and forearms) in older adults, caused by focal loss of melanocytes from cumulative UV exposure.

Question 92: Tachyphylaxis in topical steroid therapy refers to:

Decreasing response with continued use (Correct answer)
Allergic contact dermatitis
Systemic absorption
Rebound flare after stopping

Correct answer: Decreasing response with continued use

Tachyphylaxis is diminishing effectiveness of a steroid over continued application.

Question 93: A patient develops acute generalized pustular psoriasis (von Zumbusch) after abrupt withdrawal of which medication?

Antihistamines
Oral vitamin D
Systemic corticosteroids (Correct answer)
Topical emollients

Correct answer: Systemic corticosteroids

Rapid tapering or withdrawal of systemic corticosteroids can precipitate generalized pustular psoriasis.

Question 94: The first-line systemic therapy class for advanced Merkel cell carcinoma is:

Hedgehog inhibitors
PD-1/PD-L1 checkpoint inhibitors (Correct answer)
BRAF inhibitors
Anthracycline chemotherapy

Correct answer: PD-1/PD-L1 checkpoint inhibitors

Avelumab and pembrolizumab (PD-1/PD-L1 blockade) are first-line for advanced MCC.

Question 95: Which factor is a Mohs appropriate use criteria indication?

Benign nevus on the back
Tumor located on the H-zone of the face (Correct answer)
Any lesion on the trunk
Small seborrheic keratosis

Correct answer: Tumor located on the H-zone of the face

Tumors in the H-zone (high-risk mask area) of the face meet Mohs appropriate use criteria.

Question 96: Which reading strategy improves retention of dermatology texts?

Skimming without note-taking
Ignoring figures and charts
Highlighting and summarizing key points (Correct answer)
Reading passively before bed

Correct answer: Highlighting and summarizing key points

Active reading strategies like highlighting and summarizing key points significantly improve retention of complex dermatology texts. Highlighting helps identify crucial information, while summarizing forces the reader to process and synthesize the material in their own words, reinforcing understanding and memory. This engagement with the text is more effective than passive reading.

Question 97: Oral acyclovir treats which dermatologic condition?

Herpes zoster (Correct answer)
Cellulitis
Rosacea
Tinea versicolor

Correct answer: Herpes zoster

Acyclovir is an antiviral used for herpes simplex and varicella-zoster infections.

Question 98: Antimicrobial peptides such as cathelicidin (LL-37) are dysregulated in the pathogenesis of which condition?

Melasma
Ichthyosis vulgaris
Seborrheic keratosis
Rosacea (Correct answer)

Correct answer: Rosacea

Elevated cathelicidin and abnormal processing contribute to rosacea inflammation.

Question 99: Basophilic 'shadow' (ghost) cells with loss of nuclei and calcification are the diagnostic feature of which tumor?

Trichilemmoma
Syringoma
Sebaceous carcinoma
Pilomatricoma (Correct answer)

Correct answer: Pilomatricoma

Pilomatricoma (calcifying epithelioma of Malherbe) is defined by shadow (ghost) cells and dystrophic calcification.

Question 100: Which topical corticosteroid potency class is superpotent (Class I)?

Clobetasol propionate 0.05% (Correct answer)
Triamcinolone 0.1%
Desonide 0.05%
Hydrocortisone 1%

Correct answer: Clobetasol propionate 0.05%

Clobetasol propionate 0.05% is a Class I superpotent topical corticosteroid.

Question 101: Which test is most appropriate for diagnosing fungal skin infections?

Patch testing
Biopsy with immunohistochemistry
Bacterial culture
KOH prep (Correct answer)

Correct answer: KOH prep

The KOH (potassium hydroxide) prep is the most appropriate initial test for diagnosing fungal skin infections. It involves scraping skin cells and dissolving keratinocytes with KOH, which allows for direct microscopic visualization of fungal elements like hyphae and spores. This method is rapid, inexpensive, and highly effective in confirming the presence of a fungal infection, guiding prompt and accurate treatment.

Question 102: A 3-year-old with fever for 5 days shows conjunctival injection, strawberry tongue, cracked lips, and periungual desquamation. What is the diagnosis?

Measles
Stevens-Johnson syndrome
Scarlet fever
Kawasaki disease (Correct answer)

Correct answer: Kawasaki disease

Kawasaki disease features prolonged fever, mucocutaneous changes, and later periungual desquamation, requiring IVIG to prevent coronary aneurysms.

Question 103: A 22-year-old patient with fair skin presents with multiple jaw keratocysts, palmar pits, and over 15 basal cell carcinomas diagnosed since their teenage years. A germline mutation in which of the following tumor suppressor genes is the most likely underlying cause of this patient's condition?

CDKN2A
TP53
NF1
PTCH1 (Correct answer)

Correct answer: PTCH1

This patient's constellation of findings—multiple early-onset basal cell carcinomas, odontogenic keratocysts of the jaw, and palmar pitting—is classic for Nevoid Basal Cell Carcinoma Syndrome (NBCCS), also known as Gorlin syndrome. This autosomal dominant disorder is most commonly caused by a germline mutation in the PTCH1 gene, a key component of the Sonic Hedgehog signaling pathway.

Question 104: The Koebner phenomenon, where lesions appear at sites of trauma, is classically seen in which disease?

Rosacea
Psoriasis (Correct answer)
Basal cell carcinoma
Seborrheic dermatitis

Correct answer: Psoriasis

Psoriasis characteristically demonstrates the Koebner phenomenon, with new plaques forming along lines of skin injury.

Question 105: Ivermectin oral therapy is useful for which infestation?

Crusted (Norwegian) scabies (Correct answer)
Warts
Impetigo
Tinea pedis

Correct answer: Crusted (Norwegian) scabies

Oral ivermectin is effective for crusted scabies, often with topical permethrin.

Question 106: Nail pitting is a manifestation of psoriasis affecting which part of the nail unit?

Lateral nail fold
Nail matrix (Correct answer)
Hyponychium
Nail bed

Correct answer: Nail matrix

Nail pitting results from focal parakeratosis in the proximal nail matrix that sloughs off, leaving small depressions on the nail surface.

Question 107: A loss-of-function mutation in the FLG gene predisposes to atopic dermatitis by impairing production of which protein?

Desmoglein 3
Filaggrin (Correct answer)
Loricrin
Collagen VII

Correct answer: Filaggrin

FLG encodes filaggrin, essential for skin barrier integrity and hydration.

Question 108: Loss-of-function mutations in the gene encoding which of the following proteins are the strongest known genetic risk factor for the development of atopic dermatitis?

Collagen VII
Loricrin
Keratin 14
Filaggrin (Correct answer)

Correct answer: Filaggrin

Filaggrin (filament aggregating protein) is a key structural protein essential for the formation and function of the stratum corneum. Loss-of-function mutations in the filaggrin gene (FLG) impair skin barrier function, leading to increased transepidermal water loss and enhanced penetration of allergens. This is the most significant and well-established genetic predisposition for atopic dermatitis.

Question 109: Benzoyl peroxide reduces acne primarily by:

Anti-androgen effect
Blocking sebaceous glands
Oxidizing and killing C. acnes (Correct answer)
Retinoid signaling

Correct answer: Oxidizing and killing C. acnes

Benzoyl peroxide releases free oxygen radicals that are bactericidal to C. acnes.

Question 110: Which practice best supports evidence-based dermatology?

Following outdated textbook advice only
Applying current peer-reviewed guidelines to patient care (Correct answer)
Prescribing based on drug rep visits
Relying solely on personal anecdote

Correct answer: Applying current peer-reviewed guidelines to patient care

Evidence-based care integrates current best research with clinical judgment.

Question 111: Which of the following genodermatoses is characterized by a defect in nucleotide excision repair (NER), leading to extreme photosensitivity, a vastly increased risk of cutaneous malignancies at a young age, and, in some cases, progressive neurologic degeneration?

Bloom Syndrome
Xeroderma Pigmentosum (Correct answer)
Rothmund-Thomson Syndrome
Cockayne Syndrome

Correct answer: Xeroderma Pigmentosum

Xeroderma pigmentosum (XP) is the quintessential disorder of defective nucleotide excision repair (NER). This autosomal recessive condition results from mutations in genes essential for NER, the primary mechanism for repairing DNA damage caused by ultraviolet (UV) radiation. The inability to repair UV-induced photoproducts leads to extreme photosensitivity, poikiloderma in sun-exposed areas, and a more than 1,000-fold increased risk of skin cancers. Neurologic degeneration is a feature in a subset of XP complementation groups.

Question 112: What is the most common cutaneous adverse effect of prolonged high-potency topical corticosteroid use?

Hypertrichosis
Photosensitivity
Hyperpigmentation
Skin atrophy and striae (Correct answer)

Correct answer: Skin atrophy and striae

Chronic potent topical steroids cause dermal atrophy, telangiectasia, and striae.

Question 113: Civatte bodies (colloid bodies) representing apoptotic keratinocytes are most characteristically found in which disorder?

Spongiotic dermatitis
Pemphigus vulgaris
Molluscum contagiosum
Lichen planus (Correct answer)

Correct answer: Lichen planus

Civatte (colloid) bodies are apoptotic keratinocytes seen at the interface in lichen planus and other lichenoid dermatitides.

Question 114: Fibrofolliculomas, trichodiscomas, and acrochordons with renal tumors and spontaneous pneumothorax define:

Tuberous sclerosis
Cowden syndrome
Birt-Hogg-Dubé syndrome (Correct answer)
Gardner syndrome

Correct answer: Birt-Hogg-Dubé syndrome

Birt-Hogg-Dubé syndrome (FLCN mutation) features follicular hamartomas plus lung cysts, pneumothorax, and renal tumors.

Question 115: Tazarotene belongs to which class of dermatologic agents?

Keratolytic
Vitamin D analog
Topical retinoid (Correct answer)
Calcineurin inhibitor

Correct answer: Topical retinoid

Tazarotene is a topical retinoid used for psoriasis and acne.

Question 116: A panniculitis biopsy shows inflammation predominantly in the connective-tissue septa without vasculitis. What is the most likely diagnosis?

Pancreatic panniculitis
Erythema nodosum (Correct answer)
Lupus panniculitis
Erythema induratum

Correct answer: Erythema nodosum

Erythema nodosum is the prototypical septal panniculitis without vasculitis.

Question 117: A 2-year-old child develops an abrupt, symmetric, monomorphous eruption of skin-colored to erythematous papules on the face, buttocks, and extensor surfaces of the extremities. The trunk is relatively spared. The child had a mild upper respiratory infection one week prior. What is the most likely diagnosis?

Erythema multiforme
Pityriasis rosea
Gianotti-Crosti syndrome (Correct answer)
Hand, foot, and mouth disease

Correct answer: Gianotti-Crosti syndrome

Gianotti-Crosti syndrome, or papular acrodermatitis of childhood, is a post-viral exanthem characterized by a monomorphous papular eruption with a classic acral distribution (face, buttocks, extensors), typically sparing the trunk. The other conditions have different lesion morphologies and distributions; for example, erythema multiforme has target lesions, and pityriasis rosea primarily affects the trunk.

Question 118: Which topical antibiotic is combined with benzoyl peroxide to reduce bacterial resistance in acne?

Mupirocin
Metronidazole
Bacitracin
Clindamycin (Correct answer)

Correct answer: Clindamycin

Benzoyl peroxide is added to clindamycin to limit C. acnes resistance.

Question 119: Cyclosporine's principal dose-limiting toxicity in dermatology is:

Cardiotoxicity
Nephrotoxicity and hypertension (Correct answer)
Pulmonary fibrosis
Ototoxicity

Correct answer: Nephrotoxicity and hypertension

Cyclosporine, a calcineurin inhibitor, commonly causes renal impairment and hypertension.

Question 120: Erosive oral lichen planus carries a small but real risk of transforming into which malignancy?

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

Correct answer: Squamous cell carcinoma

Chronic erosive oral lichen planus has a documented low risk of progression to squamous cell carcinoma.

Question 121: Which topical agent is a calcineurin inhibitor useful in atopic dermatitis of the face?

Coal tar
Anthralin
Calcipotriene
Tacrolimus (Correct answer)

Correct answer: Tacrolimus

Tacrolimus is a topical calcineurin inhibitor that avoids steroid-induced facial atrophy.

Question 122: Progressive macular hypomelanosis is distinguished from pityriasis versicolor by which Wood's lamp finding?

Yellow-green fluorescence throughout affected areas
Folliculocentric red fluorescence in coalescing hypopigmented trunk macules (Correct answer)
Brilliant blue-white fluorescence of hypopigmented patches
No fluorescence, distinguishing it from pityriasis versicolor's yellow fluorescence

Correct answer: Folliculocentric red fluorescence in coalescing hypopigmented trunk macules

Progressive macular hypomelanosis shows pathognomonic folliculocentric red fluorescence under Wood's lamp, caused by porphyrins produced by Cutibacterium acnes colonizing follicles, unlike pityriasis versicolor's yellow-green fluorescence.

Question 123: Which histochemical stain best demonstrates amyloid deposits in the skin, showing apple-green birefringence under polarized light?

Colloidal iron
Masson trichrome
Von Kossa
Congo red (Correct answer)

Correct answer: Congo red

Congo red stains amyloid and produces apple-green birefringence under polarized light.

Question 124: Lichen planopilaris, a scarring alopecia, characteristically shows which dermoscopic finding?

Exclamation mark hairs and broken hairs
Perifollicular scaling and fibrotic white dots (Correct answer)
Yellow dots and black dots
Branching vessels and white circles

Correct answer: Perifollicular scaling and fibrotic white dots

Lichen planopilaris shows perifollicular scaling, loss of follicular openings, and fibrotic white dots (stellate scarring) on dermoscopy.

Question 125: A resident notices an attending performed a procedure on the wrong lesion site. The most professional response is to:

Alter the chart to match
Ignore it to avoid conflict
Report the error transparently through proper channels (Correct answer)
Blame the nursing staff

Correct answer: Report the error transparently through proper channels

Medical errors must be disclosed and reported transparently for patient safety.

Question 126: Necrobiotic collagen surrounded by palisading histiocytes with abundant dermal mucin is characteristic of which condition?

Necrobiosis lipoidica
Granuloma annulare (Correct answer)
Rheumatoid nodule
Sarcoidosis

Correct answer: Granuloma annulare

Granuloma annulare shows palisaded histiocytes around necrobiotic collagen with prominent mucin in the center.

Question 127: A predominantly lobular panniculitis with vasculitis and evidence of tuberculous hypersensitivity most likely represents which entity?

Erythema induratum (nodular vasculitis) (Correct answer)
Lipodermatosclerosis
Subcutaneous fat necrosis
Erythema nodosum

Correct answer: Erythema induratum (nodular vasculitis)

Erythema induratum is a lobular panniculitis with vasculitis, classically linked to tuberculous hypersensitivity.

Question 128: Chronic actinic dermatitis (CAD) is characterized by which predominant lymphocyte subset on histopathology?

CD4+ T-helper cells
Regulatory T cells (Tregs)
B cells (CD20+)
CD8+ cytotoxic T cells (Correct answer)

Correct answer: CD8+ cytotoxic T cells

CAD characteristically shows a CD8+ cytotoxic T-cell predominant infiltrate, which distinguishes it from other eczematous dermatoses that are predominantly CD4+.

Question 129: Xeroderma pigmentosum results from a defect in which DNA repair pathway?

Base excision repair
Homologous recombination
Nucleotide excision repair (Correct answer)
Mismatch repair

Correct answer: Nucleotide excision repair

Xeroderma pigmentosum is caused by defective nucleotide excision repair, impairing removal of UV-induced pyrimidine dimers.

Question 130: An adolescent presents with comedones, inflammatory papules, and pustules on the face. What is the first-line topical agent for comedonal acne?

Topical retinoid (Correct answer)
Oral isotretinoin
Oral tetracycline
Topical clindamycin alone

Correct answer: Topical retinoid

Topical retinoids are first-line for comedonal acne as they normalize follicular keratinization.

Question 131: Which drug is first-line for dermatitis herpetiformis symptom control?

Azathioprine
Rituximab
Dapsone (Correct answer)
Prednisone

Correct answer: Dapsone

Dapsone rapidly relieves the intense pruritus of dermatitis herpetiformis.

Question 132: A biopsy shows acantholysis with a 'row of tombstones' basal cell appearance and intraepidermal, suprabasal clefting. Which disease is this?

Darier disease
Bullous pemphigoid
Pemphigus vulgaris (Correct answer)
Hailey-Hailey disease

Correct answer: Pemphigus vulgaris

Suprabasal acantholysis leaving a 'row of tombstones' of basal keratinocytes is classic for pemphigus vulgaris.

Question 133: Postoperative wound infection is most commonly caused by which organism?

Candida albicans
Staphylococcus aureus (Correct answer)
Pseudomonas aeruginosa
Escherichia coli

Correct answer: Staphylococcus aureus

Staphylococcus aureus is the most common cause of surgical site infections in skin surgery.

Question 134: A pigmented lesion demonstrates nests of melanocytes at both the dermoepidermal junction and within the dermis. This architecture defines which nevus type?

Blue nevus
Junctional nevus
Compound nevus (Correct answer)
Intradermal nevus

Correct answer: Compound nevus

A compound nevus has melanocytic nests in both the epidermis (junctional component) and the dermis.

Question 135: A 5-year-old presents with honey-colored crusted erosions around the nose and mouth. What is the most common causative organism?

Pseudomonas aeruginosa
Streptococcus pneumoniae
Staphylococcus aureus (Correct answer)
Haemophilus influenzae

Correct answer: Staphylococcus aureus

Non-bullous impetigo is most commonly caused by Staphylococcus aureus.

Question 136: A 4-year-old presents with fever, a 'slapped cheek' facial erythema, followed by a lacy reticular rash on the extremities. What is the etiology?

Rubella virus
Parvovirus B19 (Correct answer)
Human herpesvirus 6
Measles virus

Correct answer: Parvovirus B19

Erythema infectiosum (fifth disease) is caused by parvovirus B19 with the classic slapped-cheek appearance.

Question 137: A biopsy of a skin lesion from a patient with suspected graft-versus-host disease (GVHD) is examined. Which of the following constellations of findings would be most characteristic of acute cutaneous GVHD?

Dense nodular lymphoid aggregates with germinal centers in the dermis
Hyperkeratosis, hypergranulosis, and a dense band-like lymphocytic infiltrate
Apoptotic keratinocytes (satellite cell necrosis) at all levels of the epidermis and a vacuolar interface dermatitis (Correct answer)
Subepidermal blister with numerous eosinophils and neutrophils

Correct answer: Apoptotic keratinocytes (satellite cell necrosis) at all levels of the epidermis and a vacuolar interface dermatitis

The hallmark of acute cutaneous graft-versus-host disease is a vacuolar interface dermatitis accompanied by lymphocytic infiltration and, most critically, evidence of keratinocyte injury in the form of apoptosis. Apoptotic keratinocytes, sometimes surrounded by lymphocytes (satellite cell necrosis), are a key feature. Hyperkeratosis and a dense band-like infiltrate are more typical of lichen planus. A subepidermal blister with eosinophils suggests bullous pemphigoid, and nodular lymphoid aggregates suggest cutaneous lymphoid hyperplasia or lymphoma.

Question 138: A child with severe recurrent blistering from minor trauma since birth has a family history of similar disease. What category of disorder should be suspected?

Dermatitis herpetiformis
Bullous impetigo
Linear IgA disease
Epidermolysis bullosa (Correct answer)

Correct answer: Epidermolysis bullosa

Inherited epidermolysis bullosa causes mechanically induced blistering from birth due to structural protein defects.

Question 139: An 80-year-old woman presents with a 1.5 cm firm, red-violaceous nodule on her sun-exposed forearm. A biopsy confirms Merkel cell carcinoma. Her physical exam reveals no clinically palpable lymphadenopathy. According to NCCN guidelines, what is the most appropriate next step for staging this patient's regional lymph node basin?

Empiric radiation therapy to the regional nodal basin
Clinical observation of the nodal basin every 3 months
Sentinel lymph node biopsy (SLNB) (Correct answer)
Complete regional lymph node dissection

Correct answer: Sentinel lymph node biopsy (SLNB)

For patients with clinically node-negative Merkel cell carcinoma, a sentinel lymph node biopsy (SLNB) is the most reliable tool for identifying subclinical (micrometastatic) nodal disease. The status of the sentinel node is a powerful prognostic factor and is critical for accurate staging and guiding decisions about adjuvant therapy, such as radiation.

Question 140: A newborn presents with a solitary, firm, flesh-colored nodule that dimples when compressed laterally (Fitzpatrick sign). What is the most likely diagnosis?

Juvenile xanthogranuloma (Correct answer)
Spitz nevus
Mastocytoma
Dermatofibroma

Correct answer: Juvenile xanthogranuloma

Juvenile xanthogranuloma is a benign yellow-orange papulonodule of infancy, though the dimple sign classically describes dermatofibroma in older patients.

Question 141: Permethrin cream is the first-line treatment for:

Molluscum
Scabies (Correct answer)
Tinea corporis
Onychomycosis

Correct answer: Scabies

Topical 5% permethrin is first-line therapy for scabies infestation.

Question 142: A patient asks for a controlled sedating medication refill early and repeatedly. The dermatologist should:

Refill without question
Report the patient to police immediately
Evaluate for misuse and check the prescription monitoring program (Correct answer)
Double the dose

Correct answer: Evaluate for misuse and check the prescription monitoring program

Prescription drug monitoring and evaluation help detect and prevent misuse.

Question 143: Allergic contact dermatitis is mediated by which immunologic mechanism?

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

Correct answer: Type IV delayed-type hypersensitivity

Allergic contact dermatitis is a T-cell-mediated type IV delayed hypersensitivity reaction.

Question 144: An infant presents with well-demarcated erythema in the inguinal folds with satellite pustules. What is the most likely cause?

Candida albicans (Correct answer)
Irritant contact dermatitis
Seborrheic dermatitis
Psoriasis

Correct answer: Candida albicans

Candidal diaper dermatitis characteristically involves the skin folds with satellite pustules, unlike irritant dermatitis which spares folds.

Question 145: Which UV wavelength range is primarily responsible for direct DNA damage forming cyclobutane pyrimidine dimers?

UVA (320-400 nm)
UVB (290-320 nm) (Correct answer)
Visible light (400-700 nm)
UVC (100-290 nm)

Correct answer: UVB (290-320 nm)

UVB is directly absorbed by DNA, generating cyclobutane pyrimidine dimers.

Question 146: Under Wood's lamp examination, vitiligo-affected skin characteristically shows:

Orange-red folliculocentric fluorescence
Yellow-green fluorescence
Coral-pink fluorescence
Bright blue-white (chalk-white) fluorescence accentuating depigmentation (Correct answer)

Correct answer: Bright blue-white (chalk-white) fluorescence accentuating depigmentation

Vitiligo shows striking bright blue-white fluorescence under Wood's lamp due to complete melanin loss, which accentuates the depigmented patches and helps reveal subclinical lesions.

Question 147: Which finding on a mycosis fungoides biopsy is most specific for the diagnosis?

Pautrier microabscesses (Correct answer)
Civatte bodies
Spongiosis
Munro microabscesses

Correct answer: Pautrier microabscesses

Pautrier microabscesses—intraepidermal collections of atypical lymphocytes—are highly specific for mycosis fungoides.

Question 148: Grouped vesicles on an erythematous base in a dermatomal distribution that does not cross the midline suggests:

Primary herpes simplex
Herpes zoster (Correct answer)
Bullous pemphigoid
Dermatitis herpetiformis

Correct answer: Herpes zoster

Herpes zoster represents reactivation of varicella-zoster virus, producing painful grouped vesicles confined to a single dermatome.

Question 149: Solar urticaria is best classified as which type of photosensitivity disorder?

Photoallergic contact dermatitis
Genetic photosensitivity syndrome
Idiopathic photodermatosis (Correct answer)
Phototoxic reaction to an exogenous agent

Correct answer: Idiopathic photodermatosis

Solar urticaria is classified as an idiopathic photodermatosis characterized by immediate urticarial wheals within minutes of sun exposure that resolve within hours.

Question 150: Colloid (Civatte) bodies seen in lichen planus represent what?

Neutrophil aggregates
Mast cell granules
Dermal mucin deposits
Apoptotic (necrotic) keratinocytes (Correct answer)

Correct answer: Apoptotic (necrotic) keratinocytes

Civatte bodies are apoptotic basal keratinocytes found in lichenoid interface dermatitis.

Question 151: Which topical agent is the first-line treatment for actinic keratosis field therapy?

Hydrocortisone
5-fluorouracil (Correct answer)
Mupirocin
Tacrolimus

Correct answer: 5-fluorouracil

Topical 5-fluorouracil is a standard field therapy for actinic keratoses, which are premalignant lesions.

Question 152: Spironolactone benefits acne in women mainly through:

Bactericidal effect
Retinoid receptor binding
Anti-androgen activity (Correct answer)
Keratolysis

Correct answer: Anti-androgen activity

Spironolactone blocks androgen receptors, reducing sebum production in hormonal acne.

Question 153: A minor presents for acne treatment without a parent. In most US jurisdictions the dermatologist should:

Follow state consent laws for minors before treating (Correct answer)
Treat without any consideration of consent rules
Require a court order
Always refuse care

Correct answer: Follow state consent laws for minors before treating

Treatment of minors must follow state-specific consent and assent laws.

Question 154: Munro microabscesses (collections of neutrophils in the stratum corneum) are a characteristic histologic feature of which condition?

Psoriasis (Correct answer)
Eczema
Dermatophytosis
Bullous pemphigoid

Correct answer: Psoriasis

Munro microabscesses in the parakeratotic cornified layer are a hallmark of psoriasis.

Question 155: For low-risk actinic keratoses, field therapy commonly uses which agent?

Systemic methotrexate
Topical 5-fluorouracil (Correct answer)
Oral isotretinoin
Intralesional interferon

Correct answer: Topical 5-fluorouracil

Topical 5-FU is a standard field-directed treatment for multiple actinic keratoses.

Question 156: A dermatologist is offered payment by a pharmaceutical company to prescribe a specific biologic. This arrangement most directly violates which principle?

Conflict of interest and anti-kickback standards (Correct answer)
Informed consent
Continuity of care
Confidentiality

Correct answer: Conflict of interest and anti-kickback standards

Accepting payment to influence prescribing violates conflict-of-interest and anti-kickback rules.

Question 157: A child has multiple dome-shaped umbilicated papules on the trunk. What is the causative agent?

Herpes simplex virus
Poxvirus (Correct answer)
Coxsackievirus
Human papillomavirus

Correct answer: Poxvirus

Molluscum contagiosum is caused by a poxvirus and produces umbilicated papules.

Question 158: The Auspitz sign, elicited by removing psoriatic scale, represents what pathologic feature?

Pinpoint bleeding from dilated dermal papillae capillaries (Correct answer)
Darier-positive urtication
Nikolsky separation
Wickham striae

Correct answer: Pinpoint bleeding from dilated dermal papillae capillaries

Scraping psoriatic scale exposes thinned suprapapillary epidermis over dilated capillaries, producing pinpoint bleeding.

Question 159: What should dermatologists do when unsure of a diagnosis?

Refer for biopsy or specialist evaluation (Correct answer)
Dismiss patient concerns
Prescribe general antibiotics
Guess and treat

Correct answer: Refer for biopsy or specialist evaluation

When a dermatologist is unsure of a diagnosis, the professional and ethical course of action is to seek further clarification rather than guessing. Referring for a biopsy provides definitive histological information, while specialist evaluation offers a second opinion or expertise in complex cases, ensuring accurate diagnosis and appropriate treatment.

Question 160: Muir-Torre syndrome links sebaceous neoplasms with an increased risk of which internal malignancy?

Thyroid carcinoma
Prostate cancer
Pancreatic adenocarcinoma
Colorectal and other Lynch-spectrum cancers (Correct answer)

Correct answer: Colorectal and other Lynch-spectrum cancers

Muir-Torre is a variant of Lynch syndrome with mismatch-repair defects predisposing to colorectal and genitourinary cancers.

Question 161: Which is the correct standard for supervising a physician assistant performing skin exams?

No supervision needed ever
Supervision consistent with state law and scope of practice (Correct answer)
PA may practice independently in all states
Supervision only for billing purposes

Correct answer: Supervision consistent with state law and scope of practice

PA supervision must follow state law and defined scope of practice.

Question 162: A febrile 1-year-old develops high fever for 3 days that abruptly resolves, then a rose-pink macular rash erupts on the trunk. What is the cause?

Group A Streptococcus
Enterovirus
Measles virus
Human herpesvirus 6 (Correct answer)

Correct answer: Human herpesvirus 6

Roseola infantum is caused by HHV-6 with high fever preceding the rash that appears after defervescence.

Question 163: Intensely pruritic burrows in the finger webs and wrists that worsen at night suggest:

Contact dermatitis
Lichen planus
Atopic dermatitis
Scabies (Correct answer)

Correct answer: Scabies

Scabies causes nocturnal pruritus with burrows in web spaces from Sarcoptes scabiei.

Question 164: Which cytokine pathway is the primary target of biologics like ustekinumab used in moderate-to-severe plaque psoriasis?

IL-12/IL-23 (p40 subunit) (Correct answer)
TGF-beta
IL-4/IL-13
IgE-mediated

Correct answer: IL-12/IL-23 (p40 subunit)

Ustekinumab blocks the shared p40 subunit of IL-12 and IL-23, central to psoriatic inflammation.

Question 165: The AJCC 8th edition changed melanoma T-staging by adding which factor for T1 tumors?

Tumor-infiltrating lymphocytes
Regression
Mitotic rate as a T1 criterion
Ulceration and a 0.8 mm cutoff defining T1a vs T1b (Correct answer)

Correct answer: Ulceration and a 0.8 mm cutoff defining T1a vs T1b

In AJCC 8, T1b is defined by thickness ≥0.8 mm or ulceration, and mitotic rate was removed as a T-category criterion.

Question 166: A painless, indurated genital ulcer (chancre) with regional lymphadenopathy is the primary lesion of:

Syphilis (Correct answer)
Chancroid
Lymphogranuloma venereum
Herpes simplex

Correct answer: Syphilis

The painless chancre of primary syphilis is caused by Treponema pallidum and heals spontaneously.

Question 167: Porphyria cutanea tarda (PCT) is caused by deficiency of which enzyme in the heme biosynthesis pathway?

Coproporphyrinogen oxidase
Uroporphyrinogen decarboxylase (UROD) (Correct answer)
Ferrochelatase
Porphobilinogen deaminase

Correct answer: Uroporphyrinogen decarboxylase (UROD)

PCT results from deficiency of uroporphyrinogen decarboxylase (UROD), causing accumulation of uroporphyrins that absorb light and generate reactive oxygen species in the skin.

Question 168: Long-term amiodarone therapy produces a distinctive skin discoloration described as:

Yellow from lipid-drug complexes in the dermis
Slate-gray to blue-gray from drug-lipofuscin complexes in dermal macrophages in sun-exposed areas (Correct answer)
Red-brown from hemosiderin deposition
Brown-black from direct melanocyte stimulation

Correct answer: Slate-gray to blue-gray from drug-lipofuscin complexes in dermal macrophages in sun-exposed areas

Amiodarone's iodine content renders it phototoxic; chronic exposure causes iodine-containing drug-lipofuscin complexes to accumulate in dermal macrophages, producing a characteristic slate-gray or blue-gray pigmentation in photoexposed skin.

Question 169: Which of the following is the defining histopathologic feature used to classify a blistering disease as 'pemphigus'?

The presence of a 'festooned' papillary dermis
Acantholysis leading to an intraepidermal split (Correct answer)
Linear deposition of IgA at the dermoepidermal junction
A subepidermal split with a neutrophil-rich infiltrate

Correct answer: Acantholysis leading to an intraepidermal split

The term 'pemphigus' refers to a group of autoimmune blistering diseases characterized by acantholysis, which is the loss of intercellular connections between keratinocytes. This loss of adhesion results in an intraepidermal blister. The level of the split (e.g., suprabasal in pemphigus vulgaris, subcorneal in pemphigus foliaceus) can vary, but acantholysis is the common pathogenic mechanism and defining histologic feature. Subepidermal splits are seen in diseases like bullous pemphigoid and dermatitis herpetiformis. Festooning is characteristic of porphyria cutanea tarda. Linear IgA deposition defines linear IgA bullous dermatosis.

Question 170: A congenital melanocytic nevus larger than 20 cm projected adult size is termed:

Nevus spilus
Giant congenital nevus (Correct answer)
Halo nevus
Small congenital nevus

Correct answer: Giant congenital nevus

Congenital melanocytic nevi projected to reach ≥20 cm in adulthood are classified as giant, carrying the highest melanoma and neurocutaneous melanosis risk.

Question 171: The four sequential stages of incontinentia pigmenti (vesicular, verrucous, hyperpigmented, hypopigmented) follow what distribution?

Dermatomes
Langer lines
Lines of Blaschko (Correct answer)
Photodistribution

Correct answer: Lines of Blaschko

The cutaneous lesions of incontinentia pigmenti evolve along the lines of Blaschko reflecting mosaicism.

Question 172: Which relaxed skin tension line orientation minimizes scar visibility?

Perpendicular to RSTLs
Diagonal at 45 degrees
Orientation is irrelevant
Parallel to RSTLs (Correct answer)

Correct answer: Parallel to RSTLs

Incisions placed parallel to relaxed skin tension lines heal with less noticeable scars.

Question 173: A benign adnexal tumor shows interconnecting cords of basaloid cells in a 'string of pearls' pattern within a fibrous stroma with ductal differentiation. Which tumor is this?

Pilomatricoma
Syringoma (Correct answer)
Trichoepithelioma
Sebaceous adenoma

Correct answer: Syringoma

Syringoma shows comma-shaped ('tadpole') ducts and basaloid cords with eccrine ductal differentiation in a sclerotic stroma.

Question 174: A 3-week-old neonate presents with multiple erythematous papules and pustules confined to the face and scalp. Examination reveals a complete absence of comedones. Which of the following is the most likely diagnosis?

Miliaria rubra
Neonatal cephalic pustulosis (Correct answer)
Erythema toxicum neonatorum
Neonatal acne

Correct answer: Neonatal cephalic pustulosis

Neonatal cephalic pustulosis is characterized by an inflammatory papulopustular eruption on the face and scalp, typically appearing around 2-3 weeks of age. The key distinguishing feature from true neonatal acne is the absence of comedones. It is thought to be an inflammatory reaction to Malassezia species. Neonatal acne presents with comedones, while erythema toxicum neonatorum appears earlier and has a different clinical appearance.

Question 175: The 'atopic triad' associated with atopic dermatitis includes asthma, allergic rhinitis, and what?

Vitiligo
Atopic dermatitis (eczema) itself (Correct answer)
Urticaria pigmentosa
Psoriasis

Correct answer: Atopic dermatitis (eczema) itself

The atopic triad comprises atopic dermatitis, allergic rhinitis, and asthma.

Question 176: Which of the following findings on a mineral oil skin scraping is considered definitive for the diagnosis of scabies?

Identification of the mite, its eggs, or its feces (scybala) (Correct answer)
A positive burrow ink test showing a zig-zag line
Peripheral eosinophilia on a complete blood count
Presence of multiple excoriations

Correct answer: Identification of the mite, its eggs, or its feces (scybala)

While clinical signs like burrows and excoriations are highly suggestive, the definitive diagnosis of scabies is made by the direct visualization of the causative agent, Sarcoptes scabiei, or its products. A mineral oil preparation of a skin scraping from a burrow allows for microscopic identification of the adult mite, eggs, or fecal pellets (scybala), confirming the infestation.

Question 177: Which immunoglobulin class is deposited in the dermal papillae in dermatitis herpetiformis?

IgG
IgA (Correct answer)
IgE
IgM

Correct answer: IgA

Granular IgA deposits in dermal papillary tips are diagnostic of dermatitis herpetiformis.

Question 178: A patient refuses a recommended skin cancer excision after being informed of the risks. The dermatologist should:

Respect the decision and document the refusal (Correct answer)
Perform the excision anyway
Threaten the patient
Discharge the patient permanently without follow-up

Correct answer: Respect the decision and document the refusal

A competent patient may refuse treatment; the refusal should be documented.

Question 179: Which suffers highest risk of motor nerve injury during temple surgery?

Temporal branch of the facial nerve (Correct answer)
Marginal mandibular nerve
Spinal accessory nerve
Great auricular nerve

Correct answer: Temporal branch of the facial nerve

The temporal branch of the facial nerve is superficial at the temple and vulnerable to injury.

Question 180: A dark-skinned infant is born with brown-gray macules and pustules that rupture leaving collarettes of scale and hyperpigmented macules. What is the diagnosis?

Erythema toxicum
Transient neonatal pustular melanosis (Correct answer)
Acropustulosis of infancy
Congenital candidiasis

Correct answer: Transient neonatal pustular melanosis

Transient neonatal pustular melanosis presents at birth with pustules that leave pigmented macules and scaly collarettes.

Question 181: The type III hypersensitivity reaction responsible for cutaneous leukocytoclastic vasculitis is mediated primarily by:

Delayed T-cell response
Immune complex deposition (Correct answer)
IgE-mediated mast cell degranulation
Cytotoxic T cells

Correct answer: Immune complex deposition

Type III reactions involve immune complex deposition in vessel walls triggering complement activation.

Question 182: Which class of biologics targeting IL-17 is highly effective for plaque psoriasis?

Etanercept
Secukinumab (Correct answer)
Infliximab
Ustekinumab

Correct answer: Secukinumab

Secukinumab is an IL-17A inhibitor with strong efficacy in plaque psoriasis.

Question 183: How does photoallergic contact dermatitis differ from phototoxic dermatitis?

Photoallergic reactions require prior sensitization and involve a Type IV immune response (Correct answer)
Phototoxic reactions can spread beyond sun-exposed areas
Phototoxic reactions require prior sensitization
Photoallergic reactions always cause blistering on first exposure

Correct answer: Photoallergic reactions require prior sensitization and involve a Type IV immune response

Photoallergic reactions require prior sensitization, involve a Type IV delayed hypersensitivity immune response, and can spread beyond directly sun-exposed sites.

Question 184: A patient on a new sulfa drug develops a well-demarcated round violaceous plaque that recurs at the same site with rechallenge. What is the diagnosis?

Contact dermatitis
Erythema multiforme
Urticaria
Fixed drug eruption (Correct answer)

Correct answer: Fixed drug eruption

A fixed drug eruption recurs at the identical location with each exposure to the offending drug.

Question 185: Atypical fibroxanthoma classically arises in which clinical setting?

Sun-damaged head and neck of elderly patients (Correct answer)
Genital skin of middle-aged women
Young immunosuppressed patients on the trunk
Palms and soles of manual laborers

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

AFX typically presents as a rapidly growing nodule on chronically sun-damaged skin of the head and neck in the elderly.

Question 186: A vascular dermal proliferation of spindle cells with slit-like spaces, extravasated red cells, and HHV-8 positivity is characteristic of which tumor?

Hemangioma
Pyogenic granuloma
Angiosarcoma
Kaposi sarcoma (Correct answer)

Correct answer: Kaposi sarcoma

Kaposi sarcoma shows slit-like vascular spaces, spindle cells, extravasated erythrocytes, and is HHV-8 positive.

Question 187: Dennie-Morgan folds and hyperlinear palms are physical clues supporting which diagnosis?

Atopic dermatitis (Correct answer)
Dermatitis herpetiformis
Pityriasis rosea
Bullous pemphigoid

Correct answer: Atopic dermatitis

Dennie-Morgan infraorbital folds and hyperlinear palms are minor stigmata of the atopic constitution.

Question 188: Which topical calcineurin inhibitor is used as a steroid-sparing agent for atopic dermatitis, especially on the face?

Tacrolimus (Correct answer)
Clobetasol
Calcipotriene
Salicylic acid

Correct answer: Tacrolimus

Tacrolimus (and pimecrolimus) are calcineurin inhibitors useful for sensitive areas without steroid atrophy risk.

Question 189: A biopsy shows a subepidermal blister with linear IgG and C3 along the basement membrane. What is the diagnosis?

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

Correct answer: Bullous pemphigoid

Bullous pemphigoid shows subepidermal tense blisters with linear IgG and C3 deposition targeting hemidesmosomal antigens.

Question 190: Erythema migrans, a target-shaped expanding rash, is the hallmark of which infection?

Cellulitis
Rocky Mountain spotted fever
Lyme disease (Correct answer)
Erysipelas

Correct answer: Lyme disease

Erythema migrans is the characteristic early lesion of Lyme disease from Borrelia burgdorferi.

Question 191: Sebaceous neoplasms plus visceral (especially colorectal) malignancies, caused by mismatch repair defects, define:

Cowden syndrome
Gorlin syndrome
Birt-Hogg-Dubé syndrome
Muir-Torre syndrome (Correct answer)

Correct answer: Muir-Torre syndrome

Muir-Torre syndrome, a variant of Lynch syndrome, pairs sebaceous tumors and keratoacanthomas with internal malignancies from MMR gene mutations.

Question 192: A KOH prep from a patient with tinea versicolor classically shows what pattern?

Acid-fast bacilli
Multinucleated giant cells
Spaghetti and meatballs (Correct answer)
Septate branching hyphae only

Correct answer: Spaghetti and meatballs

Malassezia species produce short hyphae and round yeast, described as a 'spaghetti and meatballs' appearance.

Question 193: A newborn with a large plaque-type congenital melanocytic nevus over the back is at increased risk for which condition?

Vitiligo
Psoriasis
Basal cell carcinoma
Neurocutaneous melanosis (Correct answer)

Correct answer: Neurocutaneous melanosis

Large/giant congenital melanocytic nevi carry a risk of neurocutaneous melanosis and melanoma.

Question 194: A patient presents with a tense subepidermal blister and linear IgG along the basement membrane on direct immunofluorescence. What is the diagnosis?

Linear IgA disease
Bullous pemphigoid (Correct answer)
Dermatitis herpetiformis
Pemphigus vulgaris

Correct answer: Bullous pemphigoid

Bullous pemphigoid shows tense subepidermal bullae with linear IgG and C3 at the dermoepidermal junction.

Question 195: A 3-year-old has scaly annular scalp patches with hair loss and black dots. What is the preferred treatment?

Selenium sulfide only
Topical ketoconazole shampoo alone
Topical steroid
Oral griseofulvin (Correct answer)

Correct answer: Oral griseofulvin

Tinea capitis requires systemic antifungal therapy such as oral griseofulvin because topical agents cannot penetrate the hair follicle.

Question 196: A rose-thorn puncture followed by nodules ascending along lymphatics suggests infection with:

Malassezia furfur
Trichophyton rubrum
Sporothrix schenckii (Correct answer)
Candida albicans

Correct answer: Sporothrix schenckii

Sporotrichosis (Sporothrix schenckii) causes nodular lymphangitis after inoculation, classically from rose thorns or sphagnum moss.

Question 197: Under HIPAA, a dermatology practice must:

Safeguard protected health information and limit disclosures (Correct answer)
Share records freely with anyone
Store records without any security
Post patient data publicly

Correct answer: Safeguard protected health information and limit disclosures

HIPAA requires safeguarding PHI and limiting disclosures to the minimum necessary.

Question 198: Delayed bleeding after cutaneous surgery most often occurs within what timeframe?

At 6 weeks
Within the first 24-48 hours (Correct answer)
At 2 weeks
Immediately during surgery

Correct answer: Within the first 24-48 hours

Most postoperative hematomas and delayed bleeding present within the first 24-48 hours.

Question 199: A dermal tumor shows a proliferation of spindle cells with a 'storiform' (cartwheel) pattern and entraps fat, extending into subcutis. Which is most likely?

Neurofibroma
Leiomyoma
Dermatofibrosarcoma protuberans (Correct answer)
Dermatofibroma

Correct answer: Dermatofibrosarcoma protuberans

A storiform spindle-cell proliferation infiltrating fat in a honeycomb pattern and CD34-positive is characteristic of DFSP.

Question 200: Post-inflammatory hyperpigmentation (PIH) is more persistent in darker skin types primarily because:

Both epidermal melanin deposition and dermal melanophage formation occur (Correct answer)
Keratinocyte turnover is slower
Mast cell density is higher in darker skin
Melanocytes are more numerous in darker skin

Correct answer: Both epidermal melanin deposition and dermal melanophage formation occur

PIH involves both epidermal hyperpigmentation from activated melanocytes and dermal melanophages from melanin incontinence; the dermal component is difficult to treat and accounts for prolonged PIH in darker phototypes.

American Board of Dermatology (ABD) APPLIED Certification Exam

The ABD APPLIED Exam certifies dermatologists by testing clinical application of knowledge across medical dermatology, pediatric dermatology, dermatologic surgery, and dermatopathology. It consists of 200 multiple-choice questions administered in four timed sections.

200

Questions

376 min

Time Limit

70%

To Pass

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