Hair casts: a clinical and electron microscopic study.

Hair casts were seen in 22 girls ranging in age from 4 to 13 years. They were localized to the frontal, vertex, and temporal areas. The number of affected hairs varied from one-tenth to one-third. Twenty of the 22 girls styled their hair in ponytails or pigtails. Compound root sheath casts were present in six of nine patients using 1% 4-dimethylaminocinamaldehyde stain. A mass of large polymorphous scales and solitary or clumped spores was seen on the surface of hair casts using scanning and transmission electron microscopy. Energy-dispersive x-ray microanalysis showed that elements of silicon, aluminum, and molybdenum were uniquely present in hair casts. We assume that tightly drawn braids, by causing local circulatory disturbances and inflammation of the scalp, may be one etiologic factor in the disorder.