Papillary eccrine adenoma. A light microscopic and immunohistochemical study.

The papillary eccrine adenoma is a rare benign sweat gland neoplasm characterized by a potentially locally aggressive clinical course. The light microscopic findings in two cases of this unusual neoplasm are discussed, with emphasis on the differential diagnosis of this tumor from other benign and malignant sweat gland neoplasms. Immunohistochemistry studies directed against various epithelial antigens were also performed. Immunoperoxidase stains positive for carcinoembryonic antigen, S-100 protein, and epithelial membrane antigen strongly support the hypothesis that this unusual neoplasm differentiates toward the eccrine secretory coil.