Skin & Breast Pathology MCQs: Dermatological OmpathStudy

PAPER 1: MOUNT KENYA UNIVERSITY — SCHOOL OF MEDICINE Programme: Bachelor of Medicine and Bachelor of Surgery, Year 3 Assessment: Mid of Semester 3 — CAT 1 Unit Code: MBPA 3536B — Skin and Breast Pathology Date: May 2026 --- Q1. 24-year-old woman, rapidly evolving erythematous flat, non-palpable lesion on forearm after insect bite, 1.5cm. a. Papule b. Macule c. Plaque d. Patch e. Vesicle Answer: d — Patch A flat, non-palpable lesion 1cm is a patch. Macule (b) is the same but <1cm; papule (a) and plaque (c) are raised/palpable. Q2. 32-year-old, multiple small raised fluid-filled lesions on erythematous base after poison ivy exposure, <0.5cm. a. Bullae b. Pustules c. Vesicles d. Papules e. Pimples Answer: c — Vesicles Fluid-filled lesions <0.5cm are vesicles by definition; bullae (a) are the larger ( 0.5cm) counterpart. Q3. 40-year-old woman, pruritic erythematous plaques with silvery scales on extensor elbows; parakeratosis, acanthosis, elongated rete ridges. a. Lichen planus b. Psoriasis vulgaris c. Atopic dermatitis d. Seborrheic dermatitis e. Discoid lupus erythematosus Answer: b — Psoriasis vulgaris Classic extensor-surface silvery-scaled plaques with parakeratosis and elongated rete ridges are diagnostic of psoriasis. Q4. 5-year-old child, honey-colored crusted lesions around mouth/nose, began as ruptured vesicles. a. Staphylococcus aureus b. Streptococcus pyogenes c. Herpes simplex virus d. Candida albicans e. Varicella-zoster virus Answer: a — Staphylococcus aureus Classic "honey-crusted" lesions describe impetigo, most commonly caused by S. aureus (Strep pyogenes, b, is also a recognised cause but S. aureus is now the more common one). Q5. 45-year-old woman, chronic pruritic polygonal purple papules on flexor wrists; band-like lymphocytic infiltrate at dermoepidermal junction. a. Type I hypersensitivity b. Immune complex deposition c. T-cell mediated cytotoxicity d. Autoantibodies against desmosomes e. Complement-mediated lysis Answer: c — T-cell mediated cytotoxicity This describes lichen planus; the classic band-like lymphocytic infiltrate reflects cytotoxic T-cell attack on basal keratinocytes. Q6. 50-year-old obese woman, tender erythematous nodules on anterior legs; septal panniculitis without vasculitis. a. Erythema nodosum b. Erythema induratum c. Polyarteritis nodosa d. Lipodermatosclerosis e. Lupus panniculitis Answer: a — Erythema nodosum Septal panniculitis without vasculitis, on anterior shins, is the classic description of erythema nodosum. Erythema induratum (b) involves lobular panniculitis with vasculitis instead. Q7. 70-year-old man, tense bullae on erythematous base (trunk/proximal limbs), Nikolsky sign negative; linear IgG deposition along basement membrane. a. Pemphigus vulgaris b. Bullous pemphigoid c. Dermatitis herpetiformis d. Linear IgA disease e. Epidermolysis bullosa Answer: b — Bullous pemphigoid Tense bullae, negative Nikolsky sign (subepidermal split), and linear IgG along the basement membrane are all classic for bullous pemphigoid, distinguishing it from pemphigus vulgaris (intraepidermal, Nikolsky positive). Q8. 55-year-old woman, flaccid blisters with painful oral/skin erosions — primary target antigen? a. Hemidesmosomes b. Type VII collagen c. Desmoglein 3 d. Integrins e. Laminin Answer: c — Desmoglein 3 Flaccid, easily rupturing blisters with oral involvement describe pemphigus vulgaris, caused by autoantibodies against desmoglein 3 (a desmosomal adhesion protein). Q9. 22-year-old man, pruritic urticarial lesions appearing/disappearing within hours — primary mechanism? a. Immune complex deposition b. Mast cell degranulation c. T-cell mediated cytotoxicity d. Keratinocyte apoptosis e. Neutrophil extracellular trap formation Answer: b — Mast cell degranulation Urticaria's rapid onset/resolution reflects IgE-mediated (or direct) mast cell degranulation releasing histamine. Q10. 35-year-old farmer, slowly enlarging ulcerated hand nodule; granulomatous inflammation with "cigar-shaped" fungal elements. a. Chromoblastomycosis b. Sporotrichosis c. Histoplasmosis d. Blastomycosis e. Candidiasis Answer: b — Sporotrichosis Classic occupational (rose gardener's/farmer's) fungal infection with cigar-shaped yeast forms on histology. Q11. 28-year-old HIV-positive patient, violaceous plaques on lower limbs; spindle cell proliferation with slit-like vascular spaces. a. Human herpesvirus 8 b. Human papillomavirus c. Epstein-Barr virus d. Cytomegalovirus e. Human herpesvirus 6 Answer: a — Human herpesvirus 8 This describes Kaposi sarcoma, which is causally linked to HHV-8, especially in immunocompromised/HIV-positive patients. Q12. 10-year-old child, well-demarcated scaly scalp patch with hair loss; dermatophytes on culture. a. Tinea corporis b. Tinea capitis c. Tinea cruris d. Tinea pedis e. Pityriasis versicolor Answer: b — Tinea capitis Scalp involvement with hair loss and dermatophyte infection is specifically tinea capitis (ringworm of the scalp). Q13. 48-year-old man, thickened