Dermatologist Certificate Dermatologist Certificate MCQ 5 — Questions and Answers
Question 1: Which biologic drug class is approved for moderate-to-severe plaque psoriasis and works by inhibiting IL-17A?
- TNF-alpha inhibitors
- IL-12/23 inhibitors
- IL-17A inhibitors (Correct answer)
- IL-23 inhibitors
Correct answer: IL-17A inhibitors
Secukinumab and ixekizumab are IL-17A inhibitors approved for moderate-to-severe plaque psoriasis with high efficacy.
Question 2: A patient presents with grouped vesicles on an erythematous base along a unilateral thoracic dermatome. Which antiviral is first-line?
- Acyclovir 200 mg 5x/day
- Valacyclovir 1000 mg TID (Correct answer)
- Famciclovir 500 mg BID
- Ganciclovir 5 mg/kg IV
Correct answer: Valacyclovir 1000 mg TID
Valacyclovir 1000 mg three times daily for 7 days is preferred for herpes zoster due to improved bioavailability over acyclovir.
Question 3: Pityriasis versicolor is caused by which organism?
- Candida albicans
- Malassezia furfur
- Trichophyton rubrum
- Pityrosporum orbiculare (Malassezia globosa) (Correct answer)
Correct answer: Pityrosporum orbiculare (Malassezia globosa)
Pityriasis versicolor is most often caused by Malassezia globosa (formerly classified as Pityrosporum orbiculare), a lipophilic yeast.
Question 4: Which histologic finding is pathognomonic for lichen planus?
- Pautrier microabscesses
- Max-Joseph spaces with saw-tooth rete ridges (Correct answer)
- Munro microabscesses
- Spongiform pustules of Kogoj
Correct answer: Max-Joseph spaces with saw-tooth rete ridges
Lichen planus shows vacuolar interface dermatitis with Max-Joseph spaces, saw-tooth rete ridges, and a band-like lymphocytic infiltrate.
Question 5: A 70-year-old woman has tense bullae on uninflamed skin of the thighs and lower abdomen. DIF shows linear IgG and C3 at the dermoepidermal junction. What is the diagnosis?
- Pemphigus vulgaris
- Dermatitis herpetiformis
- Bullous pemphigoid (Correct answer)
- Linear IgA bullous dermatosis
Correct answer: Bullous pemphigoid
Bullous pemphigoid presents with tense subepidermal bullae and linear IgG/C3 at the BMZ on DIF, targeting BP180 and BP230.
Question 6: Which of the following is a characteristic feature of rosacea that distinguishes it from acne vulgaris?
- Open comedones
- Cystic nodules
- Phymatous skin changes (Correct answer)
- Truncal involvement
Correct answer: Phymatous skin changes
Phymatous changes (e.g., rhinophyma) are specific to rosacea and do not occur in acne vulgaris.
Question 7: A child presents with honey-crusted erosions around the mouth and nose. Gram stain shows gram-positive cocci in clusters. What is the most likely causative organism?
- Streptococcus pyogenes
- Staphylococcus aureus (Correct answer)
- Staphylococcus epidermidis
- Enterococcus faecalis
Correct answer: Staphylococcus aureus
Non-bullous impetigo is most commonly caused by Staphylococcus aureus, which presents with honey-colored crusts in children.
Dermatologist Certificate Dermatologist Certificate MCQ 5
Which biologic drug class is approved for moderate-to-severe plaque psoriasis and works by inhibiting IL-17A?