Congenital Becker's nevus with a familial association.

Becker's nevus is a unilateral, hyperpigmented cutaneous hamartoma usually with hypertrichosis. It occurs predominantly in boys, becoming apparent during adolescence, although several cases of congenital Becker's nevus have been reported. Rarely it may be familial and as such is transmitted in an autosomal dominant pattern. We report a 16-month-old black boy with a hyperpigmented patch on his right shoulder and upper pectoral area that extended down his arm. The patient's father has a similar lesion with hair on his left shoulder which has been present since childhood. Histology of the child's lesion was consistent with Becker's nevus. We believe this to be the first reported case of a congenital Becker's nevus with a familial association.