Congenital hypotrichosis is a non-specific, descriptive term for structural abnormalities of hairs showing variable clinical features. We recently have encountered a group of eleven patients exhibiting abnormal hairs showing similar patterns.

Our purpose was to clarify the entity of this structural hair disorder.

Dermatologic examination with routine histopathology, trichograms along with scanning electron-microscopic examination and laboratory studies were undertaken.

All cases except one were female, and hair abnormalities had developed at birth or within a year. Diffuse distribution of thin, sparse, soft and hypopigmented hairs were noticed. On hair mounts, four patients showed tapering of roots. The majority of the patients exhibited cuticular changes, as well as pitting and longitudinal axial twisting by scanning electron-microscopic examination; one case demonstrated trichorrhexis nodosa, and another, trans-verse fracture.

Although our cases bear some similar points with woolly hair, some differences were noted between this type of congenital hypotrichosis and other previously described syndromes.