Pilomatrixoma of the head and neck: Typical presentation of a rare lesion.

Pilomatrixomas are benign tumours of primitive hair follicles, usually presenting as painless lumps in the head and neck region in children. As they are uncommon, they are often misdiagnosed clinically. We discuss a case of a five-year-old boy presenting with a five-month history of a pre-auricular lump. The initial clinical differential diagnosis was of a dermoid or a branchial cleft cyst. However, on ultrasonography the lesion was typical of a pilomatrixoma. The imaging literature is reviewed to illustrate the sonographic appearances of pilomatrixomas.