Question:

A 30-year-old lady comes to see you for some skin problems. Upon examination, you incidentally notice a yellowish lesion on the scalp. Asked about the lesion, the patient says it has been there since birth.

Answer: A. Naevus sebaceous

Naevus sebaceous usually presents at birth as a single flat yellowish plaque over the scalp or face. It becomes nodular or verrucous at puberty. It is an organoid naevus composed of malformation or proliferation of the epidermis, hair follicles, apocrine glands and sebaceous glands. Malignant change may occur in adulthood.