Familial occurrence of follicular keratosis of the chin.

Follicular keratosis of the chin is a rare and poorly understood pediatric disorder with a characteristic presentation of multiple follicular papules on the chin. Although prolonged friction or pressure over the chin is considered an etiology, such history is not present in most cases. It sometimes occurs within families without any evidence of physical trauma, suggesting a genetic predisposition of the patients to develop the disease. In the present study, we report two brothers with the disease, in whom no definite physical trauma was identified but comedo formation was evident. The clinical presentation of follicular keratosis of the chin is unique, particularly owing to its specific location on the chin with an age predilection from late childhood to puberty. We assume that the hormone status is an etiology of the disease since the chin is an area where androgenic hormones target at puberty and comedogenesis is a well-known biological function of the hormone. We also assumed that the susceptibility to the hormone may involve in the development of the familial follicular keratosis of the chin.