Anhidrotic ectodermal dysplasia with eruptive vellus hair cysts

A 21-year-old white man complained of heat intolerance, absence of sweating , and papular lesions on the forehead. Facial features included a saddle no se, prominent supraorbital edge, and frontal bossing. The scalp hair was sc anty, fine, and brittle. Eyelashes and eyebrows were also thin. Subungual h yperkeratosis and dystrophic changes were observed on the finger and toe na ils. Hypodontic teeth were detected on oral examination. He was otherwise h ealthy. Biochemical and hematologic analyses were also normal. Cutaneous ex amination revealed smooth and dry skin. Multiple, 4-5 mm, brown-black, come do-like, soft papules were observed on the forehead (Fig. 1). A biopsy spec imen from a papule on the forehead revealed cystic structures lined by squa mous epithelium and containing laminated keratinous material and scattered obliquely and transversely cut vellus hairs (Fig. 2). Topical application o f 0.1% tretinoin for 2 months produced no clinical improvement.