Tinea and fungal skin infection — formative SAQs

SAQ 1 — The scaly bald scalp patch (10 marks, 15 minutes)

A five-year-old boy presents with a three-week history of an itchy, scaly, gradually enlarging bald patch on his scalp. On examination there is a four-centimetre patch of hair loss with broken hair stubs and black dots flush with the skin, mild scaling, and a firm enlarged occipital lymph node. Potassium hydroxide microscopy of a plucked hair shows branching septate hyphae and arthroconidia. ^[1]

a) What is the diagnosis, and which two clinical features distinguish it from alopecia areata? (2 marks) ^[1]

b) State the definitive treatment principle for this condition and explain why a topical antifungal cream alone cannot work. (2 marks) ^[2]

c) Fungal culture returns Trichophyton tonsurans. Name the preferred oral antifungal for this species and give the weight-banded daily dose for a 22 kg child, with the duration. Justify the species-specific choice using the evidence. (4 marks) ^{[4] [5]}

d) Outline the household and public-health measures that prevent recurrence after treatment. (2 marks) ^[10]