Dermatologist Certificate General 4 — Questions and Answers
Question 1: Which of the following best describes the mechanism of action of isotretinoin in treating acne?
- Inhibits bacterial protein synthesis
- Reduces sebaceous gland size and sebum production (Correct answer)
- Blocks androgen receptors in follicles
- Increases epidermal turnover
Correct answer: Reduces sebaceous gland size and sebum production
Isotretinoin permanently reduces sebaceous gland size by up to 90%, dramatically decreasing sebum production and normalizing follicular keratinization.
Question 2: What is the first-line treatment for onychomycosis confirmed by positive fungal culture?
- Topical clotrimazole
- Oral terbinafine (Correct answer)
- Topical ciclopirox
- Oral fluconazole
Correct answer: Oral terbinafine
Oral terbinafine for 12 weeks is first-line for toenail onychomycosis due to its high cure rate and fungicidal mechanism against dermatophytes.
Question 3: A patient presents with targetoid lesions after starting trimethoprim-sulfamethoxazole. Mucosal involvement affects two sites. What is the diagnosis?
- Erythema multiforme major
- Stevens-Johnson syndrome (Correct answer)
- Toxic epidermal necrolysis
- Fixed drug eruption
Correct answer: Stevens-Johnson syndrome
Stevens-Johnson syndrome involves mucosal involvement at ≥2 sites with epidermal detachment affecting <10% of body surface area, often triggered by drugs.
Question 4: Dermatitis herpetiformis is characterized by deposits of which immunoglobulin in the dermal papillae?
- IgG
- IgM
- IgA (Correct answer)
- IgE
Correct answer: IgA
Dermatitis herpetiformis shows granular IgA deposits in the dermal papillae on direct immunofluorescence, associated with celiac disease.
Question 5: Which ABCDE criterion for melanoma evaluation stands for 'Evolution'?
- The lesion is asymmetric
- The lesion has changed over time (Correct answer)
- The lesion has multiple colors
- The lesion has irregular borders
Correct answer: The lesion has changed over time
The 'E' in ABCDE stands for Evolution — any change in size, shape, color, or a new symptom such as bleeding is a warning sign of melanoma.
Question 6: Seborrheic dermatitis preferentially affects which areas?
- Dorsal hands and extensor surfaces
- Scalp, nasolabial folds, and central chest (Correct answer)
- Flexural creases and groin
- Lower legs and dorsal feet
Correct answer: Scalp, nasolabial folds, and central chest
Seborrheic dermatitis affects sebum-rich areas including the scalp, face (nasolabial folds, eyebrows), and upper trunk due to Malassezia overgrowth.
Question 7: Which finding on histopathology is pathognomonic for psoriasis?
- Spongiosis with eosinophils
- Munro microabscesses in the stratum corneum (Correct answer)
- Dyskeratotic cells at all levels
- Subepidermal blister with neutrophils
Correct answer: Munro microabscesses in the stratum corneum
Munro microabscesses — collections of neutrophils in the stratum corneum — are a pathognomonic histological feature of psoriasis.
Dermatologist Certificate General 4
Which of the following best describes the mechanism of action of isotretinoin in treating acne?