Aplasia cutis with 'hair collar sign'

A 2-month-old boy was referred to our paediatric dermatological department with two adjacent oval patches of 2x3 cm in diameter, covered by a thin, atrophic, translucent membrane. The larger lesion was surrounded by tufts of darker terminal hair, that were horizontally arranged and oriented towards the periphery of the lesion, starting from the vertex ( figure 1 ). There were no palpable underlying bone abnormalities. The infant was otherwise healthy. A MRI of the brain was normal. The clinical diagnosis was membranous aplasia cutis congenita (ACC) of the scalp with the 'hair collar sign'.

ACC is a rare congenital malformation characterised by well-circumscribed absence of skin that involves the epidermis, dermis and subcutaneous fat. 1 2 The...