Heterotropic brain tissue presenting as bald cysts with a collar of hypertrophic hair. The 'hair collar' sign.

We report the cases of two children who were each noted at birth to have a single bald compressible nodule on the scalp that was surrounded by a collar of hypertrophic hair. One of the mothers had taken doxylamine succinate during pregnancy. Extensive investigations and, finally, surgery revealed that the lesions were heterotropic brain tissue without connection to the brain. Encephaloceles may also have a "hair collar." The presence of a hair collar around any cutaneous lesion should alert the clinician to the possibility of a neuroectodermal defect. All procedures on these lesions should be delayed until appropriate investigations have excluded any connection with the underlying nervous system.