ANHIDROTIC ECTODERMAL DYSPLASIA - PATHOLO GICAL DIFFERENTIATION OF HAIR-FOLLICLES AND SWEAT GLANDS AND LEADS TO DISTURBED KERATINIZATION

We report on an 11-year-old female patient with anhidrotic ectodermal dysplasia (AED) showing the following characteristics: (1) reduced num ber of hair follicles and incomplete formation of sweat glands; (2) di sturbed hair growth with shortening of anagen and anhidrosis; (3) dist urbed cytokeratin expression pattern of CK 13, 14, 19 (follicular epit helium) and of CK 18 (eccrine sweat glands); (4) reduction of cystine and increase in sulphonic cysteine acid. Thus, we demonstrated patholo gical differentiation on the immunomorphological and on the biochemica l level, leading to disturbed keratinization that could be visualized by transmission and scanning electron microscopical studies of the hai r shafts. According to these findings AED is a developmental defect th at involves not only incomplete formation of hair follicles and sweat glands but also a disordered differentiation and follicular keratiniza tion with disturbed cytokeratin pattern and pathological amino acid co mposition of the terminal hairs produced.