Woolly hair nevus

Definition

Woolly hair nevus (WHN) is a rare non-familial hair anomaly characterized by kinky, tightly coiled, and hypopigmented fine hair with an average diameter of 0.5 cm, noted, since birth or during the first two years of life, in a localized circumscribed distribution on the scalp. Occassionally, WHN grows in areas observed to be alopecic in the neonatal period. WHN can be associated with features like ocular defects (persistent pupillary membrane, retinal defects), precocious puberty, and epidermal nevi.