Woolly hair nevus. Two case reports and a discussion of unruly hair forms

Abstract

Woolly hair is very curly hair that is characteristically unruly and will not form naturally into locks. Woolly hair nevus first appears when the scalp hair begins to grow. It is seen as a patch of unruly, very curly hair, arising in a field of otherwise unremarkable scalp hair. Woolly hair can also be seen as a hereditary trait involving the entire scalp and in acquired forms. It may be distinguished from two other types of unruly hair, pili torti and spun glass hair.

The genetics of hair shaft disorders

“…131 Hairs are tightly curled, with an average curl diameter of 0.5 cm, 221 and can also contain wide twists over several millimeters along its own longitudinal axis. 222 It was originally described by Hutchinson 221 as ''pseudopili-torti.'' Hair shafts are ovoid, flattened, or irregular.…”

“…Hair shafts are ovoid, flattened, or irregular. [221][222][223] Associated hair findings may include increased hair fragility, TN, 224 trichoschisis, and pili annulati (PA). 221 The rate of hair growth is typically normal (approximately 1 cm/month), and the composition of keratin and amino acids do not differ from normal hair.…”

Woolly hair naevi with systematized linear epidermal naevus

“…This anomaly of hair growth was first described as 'a peculiar form of birthmark of the hair of the scalp', and was named 'woolly hair naevus' by Wise in 1927-It is a rare condition: Lantis and Pepper (1978) have reviewed the 12 cases which have been reported since the original description and added two more cases of their own. In eight of these 14 cases, there is an associated linear epidermal naevus, usually ipsilateral.…”

A practical, algorithmic approach to diagnosing hair shaft disorders

“…This structural asymmetry causes the coiling and crimping of wool. 21 Human hair may also at times have a woolly appearance even though it consists mainly of paracortex, and the explanation of the woolly appearance is incomplete. Woolly hair can involve the entire scalp 22 or just an isolated patch seen as a woolly hair nevus.…”