Photoclinic: Aplasia Cutis Congenita With the "Hair Collar Sign"

The parents of this 4-month-old infant were concerned about an atrophic, 0.6-cm area on their son's parietal scalp that was surrounded by dark hair. The rest of the scalp was normal, and the child was otherwise healthy. Benjamin Barankin, MD, of Edmonton, Alberta, made the clinical diagnosis of the hair collar sign--growth of long, dark, coarse hair around a scalp lesion that may be a marker for underlying defects. The sign is sometimes found in association with aplasia cutis congenita, in which a portion of skin is absent--most commonly this manifests as a solitary round lesion on the scalp. These lesions may have healed at birth with a scar or they may remain eroded or ulcerated.