Light microscopic hair abnormalities in children: retrospective review of 119 cases in a 10-year period.

Abnormalities in the hair can be congenital or acquired conditions. Examples of genetic disorders with associated hair abnormalities include Menkes syndrome, Netherton syndrome, uncombable hair syndrome, trichothiodystrophy, and loose anagen hair syndrome. Acquired hair abnormalities can be associated with grooming or use of various hair products. There are many patterns of hair abnormalities that can be readily identified under a light microscope. We performed a retrospective review of 129 hair mount samples from 119 patients submitted to the pathology department for microscopic examination over a 10-year span (from January 2002 to December 2011). Of the 119 patients, 63 (53%) had morphologic changes in the hair samples. Thirty-seven patients (31%) showed morphologic changes compatible with specific diagnoses of various genetic conditions, including 25 cases of loose anagen hair syndrome, 6 cases of uncombable hair syndrome, 2 cases of Netherton syndrome, 3 cases of Menkes syndrome, and 1 case of trichothiodystrophy. The other changes were considered nonspecific or nondiagnostic, with trichorrhexis nodosa in 13 patients, presence of loose anagen hairs in 12 patients, and pili torti in 1 patient. We describe the light microscopic patterns of hair abnormalities, clinical findings, and molecular defects related to those genetic conditions. Our study indicates that hair examination can be a 1st-line investigation on various pediatric conditions.