CDT Dermatologic Conditions & Diseases 2 — Questions and Answers
Question 1: A patient presents with well-demarcated, erythematous plaques covered with silvery-white scales on the elbows and knees. Which condition is most likely?
- Seborrheic dermatitis
- Psoriasis vulgaris (Correct answer)
- Pityriasis rosea
- Nummular eczema
Correct answer: Psoriasis vulgaris
Psoriasis vulgaris characteristically presents with well-demarcated erythematous plaques with silvery-white scales on extensor surfaces like elbows and knees.
Question 2: Which dermatophyte infection specifically affects the nails?
- Tinea corporis
- Tinea pedis
- Onychomycosis (Correct answer)
- Tinea versicolor
Correct answer: Onychomycosis
Onychomycosis is fungal infection of the nails, causing thickening, discoloration, and brittleness.
Question 3: A 65-year-old with a history of sun exposure presents with a rough, scaly lesion on the face. Biopsy reveals atypical keratinocytes in the epidermis without invasion. What is the diagnosis?
- Squamous cell carcinoma
- Actinic keratosis (Correct answer)
- Keratoacanthoma
- Bowen's disease
Correct answer: Actinic keratosis
Actinic keratosis (solar keratosis) shows atypical keratinocytes confined to the epidermis, making it a precancerous lesion rather than frank carcinoma.
Question 4: Which type of urticaria is caused by physical stimuli such as pressure, cold, or heat?
- Allergic urticaria
- Cholinergic urticaria
- Physical urticaria (Correct answer)
- Dermatographism
Correct answer: Physical urticaria
Physical urticaria is triggered by external physical stimuli including cold, heat, pressure, vibration, or exercise.
Question 5: Stevens-Johnson syndrome (SJS) is best described as:
- A superficial fungal infection of mucosal surfaces
- A severe mucocutaneous drug reaction with epidermal detachment affecting less than 10% BSA (Correct answer)
- A chronic blistering autoimmune disorder
- An inherited disorder of keratinization
Correct answer: A severe mucocutaneous drug reaction with epidermal detachment affecting less than 10% BSA
SJS is a severe mucocutaneous hypersensitivity reaction, most often drug-induced, characterized by epidermal detachment involving less than 10% of body surface area.
Question 6: A newborn presents with a large, superficial blister that ruptures easily, leaving a moist denuded area. Gram stain shows gram-positive cocci in clusters. What is the most likely diagnosis?
- Epidermolysis bullosa
- Bullous impetigo
- Staphylococcal scalded skin syndrome (Correct answer)
- Pemphigus vulgaris
Correct answer: Staphylococcal scalded skin syndrome
Staphylococcal scalded skin syndrome in neonates is caused by exfoliative toxins from Staphylococcus aureus, causing widespread superficial blistering and desquamation.
Question 7: Which finding on dermoscopy is most associated with melanoma?
- Arborizing vessels
- Atypical pigment network with regression structures (Correct answer)
- Milia-like cysts
- Comma-shaped vessels
Correct answer: Atypical pigment network with regression structures
Atypical pigment network, regression structures (white scar-like areas or blue-gray peppering), and irregular streaks are key dermoscopic features of melanoma.
CDT Dermatologic Conditions & Diseases 2
A patient presents with well-demarcated, erythematous plaques covered with silvery-white scales on the elbows and knees.
Which condition is most likely?