A case of hypotrichosis simplex of the scalp

We report a sporadic case of hypotrichosis simplex of the scalp, a rare genotrichosis, characterized by sparse or absent scalp hair with no structural defect of the hair shaft, in the absence of other ectodermal or systemic abnormalities. A 9-year-old girl had normal-looking hair at birth but subsequently lost the hair on her scalp after she turned 3 years of age. However, her eyebrows and eyelashes remained normal. Skin, nails and teeth were also normal except for malocclusion. No other family member had a similar hair defect. Hak shaft examination did not reveal any structural abnormalities. Microscopic examination of a scalp biopsy specimen showed a reduced number of hair follicles.