Papillary eccrine adenoma--a light-microscopic and immunohistochemical study.

We report a case of papillary eccrine adenoma. This benign cutaneous tumour had a diagnostic microscopic appearance that consisted of multiple dilated ducts lined by two or more layers of cells. The inner layer often formed intraluminal papillary projections of variable complexity. The lumina were filled by eosinophilic amorphous material. Immunoperoxidase studies showed carcino-embryonic antigen in the luminal border of the ducts, but S-100 protein was absent for tumoral ducts. We discuss the eccrine and apocrine differentiation of this neoplasm on the basis of the immunoperoxidase results. The differential diagnosis includes other cutaneous neoplasms with intraductal papillary proliferation.