Hair Follicle Miniaturization in a Woolly Hair Nevus

Abstract

Woolly hair nevus is a mosaic disorder characterized by unruly, tightly curled hair in a circumscribed area of the scalp. This condition may be associated with epidermal nevi. We describe an 11-year-old boy who initially presented with multiple patches of woolly hair and with epidermal nevi on his left cheek and back. He had no nail, teeth, eye, or cardiac abnormalities. Analysis of plucked hairs from patches of woolly hair showed twisting of the hair shaft and an abnormal hair cuticle. Histopathology of a woolly hair patch showed diffuse hair follicle miniaturization with increased vellus hairs.

Woolly hair nevus: case report and review of literature

“…Affected scalp had a reduced anagen-to-telogen ratio of A:T=4.2:1, whereas unaffected scalp had an anagen-to-telogen ratio of A:T=8:1. The mean diameter of woolly hair shafts (63±19.6μm) was significantly smaller than normal hair shafts (88±3.2μm), [11].…”

“…There is no effective treatment. Improvement has been reported with topical minoxidil 5% in an 11year-old boy, but the hair relapsed on suspension of the therapy [11]. The woolly hair may become darker and less curly with the years in some patients [7].…”