Hereditary hypotrichosis of the scalp.

Hypotrichosis of the scalp was found in 4 individuals of a 6-generation Caucasian family. This congenital phenomenon is a rather rare subtype of hereditary hypotrichosis and affects only scalp hair. The hairs of the scalp were generally sparse and short vellus type from childhood and thinned progressively with age. Morphologic studies showed poor imbrication of cuticles and dysplastic bulbar structure of the anagen follicles. The density of hair follicles per/cm2 area was comparatively lower than that of normal individuals. The genealogical study and histomorphometrical findings of this autosomal dominant trait are discussed along with previously reported causes of hypotrichosis.