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
[{'content': "Which of the following describes a Cock's peculiar tumour? \nSelect and explain. \nA. An infected sebaceous cyst, B. A malignant tumour of the scalp, C. A metastatic lesion of the scalp, D. An indicator of underlying osteomyelitis", 'role': 'user'}, {'content': "Answer: A \nExplanation: Cocks peculiar tumour is a complication of sebaceous cyst. It occurs when the surface of the sebaceous cyst gets ulcerated leading to the formation of a painful, fungating mass with discharge. It often resembles epithelioma. Sebaceous cyst is a retention cyst which result from a blockage of the duct of the sebaceous gland causing a cystic swelling. It has a putty like consistency with a parasite in the wall of the sebaceous cyst called demodex folliculorum. Other complications of a sebaceous cyst are: Infection and abscess Sebaceous horn formation which result from hardening of a slowly discharged sebum through the punctum. Ref: Srb's Manual of Surgery by Bhat By Jaypee Brothers, page 22.", 'role': 'assistant'}]