Cock's peculiar tumour is: September 2007: (A) Infected sebaceous cyst, (B) Osteomyelitis of skull, (C) Cyst in the skull, (D) Tumour of the skull
Answer is A. Ans. A: Infected sebaceous cyst Cock's peculiar tumour is a sebaceous cyst linked growth. One form of sebaceous cyst is the trichilemmal cyst; these are thought to arise from the hair follicle epithelium and are most commonly found on the scalp. Usually they are multiple but occasionally there can be a proliferating trichilemmal cyst which grows to a large size and ulcerates. These can resemble a squamous cell carcinoma (both clinically and histologically) and these ulcerating solitary cysts are called Cock's peculiar tumour.