AMC MCQ Musculoskeletal and Dermatology 3 — Questions and Answers
Question 1: A 6-year-old has an itchy, well-demarcated honey-coloured crusted lesion around the nose and mouth. What is the most likely diagnosis?
- Impetigo (Correct answer)
- Eczema herpeticum
- Atopic dermatitis
- Tinea corporis
Correct answer: Impetigo
Honey-coloured crusting is the classic appearance of impetigo, usually caused by Staphylococcus aureus.
Question 2: Which organism most commonly causes cellulitis?
- Streptococcus pyogenes (Correct answer)
- Pseudomonas aeruginosa
- Candida albicans
- Herpes simplex virus
Correct answer: Streptococcus pyogenes
Group A streptococcus and Staphylococcus aureus are the leading causes of cellulitis.
Question 3: A patient develops a target-shaped lesion with concentric rings after a recent herpes infection. What is the diagnosis?
- Erythema multiforme (Correct answer)
- Urticaria
- Psoriasis
- Pityriasis rosea
Correct answer: Erythema multiforme
Target lesions following herpes simplex are characteristic of erythema multiforme.
Question 4: Which feature distinguishes psoriasis plaques on examination?
- Silvery scale over extensor surfaces with Auspitz sign (Correct answer)
- Honey-coloured crust
- Central clearing with raised border
- Greasy yellow scale on the scalp
Correct answer: Silvery scale over extensor surfaces with Auspitz sign
Well-demarcated plaques with silvery scale and pinpoint bleeding (Auspitz sign) typify psoriasis.
Question 5: A pigmented skin lesion shows asymmetry, irregular borders, colour variation and a diameter over 6mm. What is the most concerning diagnosis?
- Malignant melanoma (Correct answer)
- Seborrhoeic keratosis
- Dermatofibroma
- Solar lentigo
Correct answer: Malignant melanoma
The ABCDE criteria raise strong suspicion of malignant melanoma.
Question 6: What is the most common type of skin cancer?
- Basal cell carcinoma (Correct answer)
- Squamous cell carcinoma
- Melanoma
- Merkel cell carcinoma
Correct answer: Basal cell carcinoma
Basal cell carcinoma is the most common skin malignancy, typically slow-growing with a pearly rolled edge.
Question 7: A young adult presents with an oval 'herald patch' followed days later by a 'Christmas tree' distribution of scaly lesions on the trunk. What is the diagnosis?
- Pityriasis rosea (Correct answer)
- Tinea versicolor
- Secondary syphilis
- Guttate psoriasis
Correct answer: Pityriasis rosea
A herald patch followed by a fir-tree pattern is classic for pityriasis rosea.
AMC MCQ Musculoskeletal and Dermatology 3
A 6-year-old has an itchy, well-demarcated honey-coloured crusted lesion around the nose and mouth.
What is the most likely diagnosis?