Loose anagen hair in a child with Noonan's syndrome.

We report on a 4 1/2-year-old girl affected by loose anagen hair and Noonan's syndrome. The girl had short, blond, easily pluckable hair that had never been cut. The trichogram showed an absolute prevalence of abnormally shaped anagen bulbs lacking inner and outer root sheaths. A scalp biopsy evidenced a marked cleft formation between fragmented inner root sheaths and irregularly shaped hair shafts.