ABD General MCQ 3 — Questions and Answers
Question 1: Which dermatophyte finding on KOH prep confirms a diagnosis of tinea?
- Pseudohyphae with budding yeast
- Septate branching hyphae (Correct answer)
- Spaghetti and meatballs pattern
- Multinucleated giant cells
Correct answer: Septate branching hyphae
Dermatophyte infections show septate, branching hyphae on KOH microscopy.
Question 2: The 'spaghetti and meatballs' appearance on KOH is characteristic of which organism?
- Trichophyton rubrum
- Malassezia furfur (Correct answer)
- Candida albicans
- Sarcoptes scabiei
Correct answer: Malassezia furfur
Malassezia furfur, the cause of tinea versicolor, produces the short hyphae and round spores described as spaghetti and meatballs.
Question 3: Which cutaneous finding is a recognized marker of internal malignancy?
- Acanthosis nigricans (Correct answer)
- Cherry angioma
- Seborrheic keratosis
- Dermatofibroma
Correct answer: Acanthosis nigricans
Sudden, widespread acanthosis nigricans can be a paraneoplastic sign, classically of gastric adenocarcinoma.
Question 4: A dermatologist notes Wickham striae on violaceous, flat-topped papules on the wrists. What is the diagnosis?
- Psoriasis
- Lichen planus (Correct answer)
- Discoid lupus
- Secondary syphilis
Correct answer: Lichen planus
Purple, polygonal, pruritic, planar papules with fine white reticular Wickham striae are diagnostic of lichen planus.
Question 5: Which layer of the epidermis is absent in thin skin but present in thick skin such as the palms?
- Stratum basale
- Stratum spinosum
- Stratum lucidum (Correct answer)
- Stratum corneum
Correct answer: Stratum lucidum
The stratum lucidum is a translucent layer found only in thick, glabrous skin of the palms and soles.
Question 6: 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)
- Dermatitis herpetiformis
- Epidermolysis bullosa simplex
Correct answer: Bullous pemphigoid
Bullous pemphigoid shows subepidermal tense blisters with linear IgG and C3 deposition targeting hemidesmosomal antigens.
Question 7: Which malignant melanoma subtype is most common on the palms, soles, and nail beds, particularly in darker-skinned patients?
- Superficial spreading melanoma
- Nodular melanoma
- Acral lentiginous melanoma (Correct answer)
- Lentigo maligna melanoma
Correct answer: Acral lentiginous melanoma
Acral lentiginous melanoma arises on palms, soles, and subungual sites and is the most common melanoma subtype in people with darker skin.
ABD General MCQ 3
Which dermatophyte finding on KOH prep confirms a diagnosis of tinea?