Hidrotic ectodermal dysplasia. Report of a case with reticulated acropigmentation.

A 22-year-old black man noted punctate macular hyperpigmentation of the distal dorsal extremities around the age of 5 years. The hyperpigmentation progressed proximally and became confluent, forming a reticulated pattern. Dermatopathology revealed increased basal melanization. Keratosis palmaris et plantaris began at the age of 19 and steadily became more severe. Body and facial hair was scant, and scalp hair required cutting once every 2 years. Teeth developed normally but were carious. Fingernails were normal, but all toenails demonstrated thickening and transverse imbrications. Sperm counts were consistently below 25 million/ml; no family members were similarly affected.