Squamous cell carcinoma arising in a subcutaneous dermoid cyst.

A case of malignant transformation to a squamous cell carcinoma in a long-standing subcutaneous dermoid cyst in a 44 year old man is presented. Malignant transformation in dermoid cysts is extremely uncommon and has never previously been recorded at this site. The need for adequate investigation and treatment of superficial midline lesions presenting in childhood is emphasized.