The woolly hair nevus is very rare non-hereditary disorder of the scalp.
Hutchinson et al had proposed a classification for woolly hair as hereditary woolly hair, familial woolly hair, symmetrical circumscribed allotrichia, woolly hair nevus. (5) Woolly hair nevus is a rare, non-hereditary condition characterized clinically by one or more, well circumscribed areas of curly/kinky hair on the scalp in a non-black individual.
Post divided the woolly hair nevus into three categories: a) Type 1: with no associated scalp disorder or hair less skin, b) Type 2: with associated linear verrucous nevus, c) Type 3: acquired, in young adults with short, dark, kinky hair, which has been termed acquired progressive kinking of scalp hair.
Clinically, the woolly hair nevus is characterized by its presence from birth or within first two years of life with one or more well circumscribed areas of the scalp of curly, kinky, shiny hair, of woolly texture, somewhat thinner and lighter in color from the remaining hair.
In more than half of the cases reported, woolly hair nevus is associated with verrucous epidermal nevus.
(10) Histological evaluation is varied in literature and in general, the woolly hair nevus is more of a clinical diagnosis.
Woolly hair nevus may be differentiated from other form of woolly hair by being congenital, limited to well demarcated areas of scalp and by abnormal microscopic findings.
A case of woolly hair nevus. Arch Dis Child 1960; 35: 512-514.
woolly hair nevus: report of a case associated with a verrucous epidermal nevus in the same area.
Woolly hair nevus. A peculiar form of birthmark of the hair the scalp, hitherto undescribed, with report of two cases.