Congenital inclusion dermoid cysts of the scalp.

The natural history of congenital inclusion dermoid cysts of the scalp is unknown. We report three cases of this condition, which has been followed from birth for up to ten years. Dermoids are congenital subcutaneous cysts, which gradually flatten and scar over a number of years. The lesions are covered with skin showing focal alopecia but they may be surrounded by a collar of hypertropic hair. Later in life flattened cysts may be mistaken for aplasia cutis, but the history of a cyst at birth allows the clinician to distinguish these two conditions. As these cysts have a potential for intracranial extension, this is an important clinical entity.