This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Cock's peculiar tumour is - 
Select and explain. 
A. An infected sebaceous cyst, B. A malignant tumour of the scalp, C. A metastatic lesion of the scalp, D. An indicator of underlying osteomyelitis
A: An infected sebaceous cyst
Answer: A: An infected sebaceous cyst 
Explanation: Ans. 'a' An infected sebaceous cyst Cocks peculiar tumour is actually a complication of sebaceous cyst. When the sebaceous cyst of the scalp ulcerates excessive granulation tissue forms resembling fungating epithelioma.This is called cock's peculiar tumour. Also know these terms Cylindroma? - A malignant epithelial tumour also k/a Turban tumor - Known as cylindroma because of histological appearance Pilomatrixoma (Calcifying epithelioma of Malherbe) ? - It is a benign hair follicle derived tumour. Pott's puffy tumour ? It is osteomyelitis of the skull associated with subperiosteal swelling and edema.