AMC MCQ Musculoskeletal and Dermatology 3

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?

Accepted Answer

Impetigo

Answer

Honey-coloured crusting is the classic appearance of impetigo, usually caused by Staphylococcus aureus.

Question 2

Which organism most commonly causes cellulitis?

Accepted Answer

Streptococcus pyogenes

Answer

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?

Accepted Answer

Erythema multiforme

Answer

Target lesions following herpes simplex are characteristic of erythema multiforme.

Question 4

Which feature distinguishes psoriasis plaques on examination?

Accepted Answer

Silvery scale over extensor surfaces with Auspitz sign

Answer

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?

Accepted Answer

Malignant melanoma

Answer

The ABCDE criteria raise strong suspicion of malignant melanoma.

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