Answer to last month's Clinical Quiz

Question:

A 5 years old boy presented with a 1cm diameter orange yellow plaque on left parietal scalp since birth. The lesion was asymptomatic, and there was no other body lesion.

Answer: C. Naevus sebaceous

Naevus sebaceus is a congenital malformation of sebaceous differentiation that occurs characteristically on the scalp, and occasionally on the face. They have a characteristic yellow orange colour, and present at birth as a fairly flat hairless plaque, with a smooth waxy surface, linear or oval in shape. They have a tendency to become raised, warty and irritable after puberty. There is an increased risk of basal cell carcinoma developing within the lesion in early adult life. Therefore prophylactic surgical removal of naevus sebaceous is recommended in the second or third decade of life.

Seborrhoeic keratosis occurs in middle age or elderly, usually on the trunk and face but occasionally on the scalp. It starts as small yellow papules, that later become darkly pigmented warty nodules with a "stuck on" appearance.

Xanthelesma are yellowish plaques on the medial eyelids of adults, and they may be associated with hypercholesterolaemia.

Alopecia areata is a sharply defined round or oval area of localised hair loss with no sign of visible inflammation, affecting the scalp or eyebrows. The area of hair loss has normal appearing skin with no scarring. Diagnostic broken off stubby hairs called "exclamation mark hairs" may be visible at the margin of the lesion.