Sclerosing sweat duct-like carcinoma of the tongue-a case report and a review of the literature.

In this article, we present the second case of a tongue carcinoma with distinct morphological similarities to a primary sclerosing sweat duct carcinoma of the skin. The tumor infiltrated deeply into the striated muscle and exhibited extensive peri- and intraneural growth. Neoplastic cells had mildly pleomorphic nuclei and displayed in addition to small cysts, distinct duct formation with a bilayered epithelium. Mitotic figures were scarce. Despite extensive sampling, no precursor lesion-dysplasia-was found. The immunochemical study showed positive reaction for carcinoembryonic antigen, epithelial membrane antigen, cytokeratin (CK)7, low-molecular weight CK, BerEp4, high-molecular weight CK, CK5, and CK18. p63 was positive in the peripheral parts of the neoplastic ducts with negative reaction in the luminal cells.