PAPILLARY ECCRINE ADENOMA - IMMUNOHISTOCHEMICAL STUDIES OF KERATIN EXPRESSION

Despite various studies, there are serious disagreements about the cel lular differentiation of papillary eccrine adenoma. In the present stu dy, 2 specimens of papillary eccrine adenoma were analyzed by immunohi stochemical techniques, using a panel of monoclonal antibodies against keratins, to elucidate its differentiation. Histopathologically, the tumor was composed of multiple tubular structures lined by two or more layers of epithelial cells. The luminal cells of tile tubules were fl attened or cuboidal. The former were noted in large dilated tubules. T he latter were usually observed in small-to-moderate-sized tubules, an d formed intra-luminal papillary projections in some tubules. Immunohi stochemically there were two kinds of cuboidal cells in the luminal la yers of the tubules. Most of tile large dilated tubules and some of th e small-to-moderate-sized tubules expressed immunophenotypes similar-t o those of the eccrine dermal duct. The other tubular structures, incl uding the small tubules resembling those of syringoma, expressed immun ophenotypes similar to those of the transitional portions between tile dermal ducts and the secretory segments of eccrine glands. From the a bove comparative studies, papillary eccrine adenoma is considered to d ifferentiate towards the dermal duct and the transitional portions bet ween the dermal ducts and the secretory segments of eccrine glands. (C ) Munksgaard 1997.