The hair collar sign - a possible indication of cranial dysraphism.

The presence of a circumscribed area of alopecia on the scalp raises several differential diagnostic considerations. A ring of hypertrichosis around such a lesion is called "hair collar sign" and raises suspicion of ectopic neural tissue and an underlying defect of the skull. We report two cases of male newborns with a hair collar surrounding a small localized area of scalp alopecia. In one child a cephalocele was diagnosed radiologically. In the other child an osseous defect was ruled out, and the histological examination confirmed the diagnosis of rudimentary meningocele after complete excision. The importance of this clinical sign has not been addressed in the German dermatological literature.