Clear-Cell Variant of Mucoepidermoid Carcinoma in the Parotid Gland:Case report and immunohistochemical study

We reported a case of a clear-cell variant, which is a histologically rare type of mucoepidermoid carcinoma, arising from the parotid gland of a 38-year-old Japanese female. Microscopically, most of the tumor nests were composed of clear cells surrounded by cuboidal epidermoid cells. A part of the tumor nest appeared to have tubular structures without clear cells. Although most of the clear cells had no reaction to PAS , alcian blue or mucicarmine, a few isolated clear cells showed positive reactions. Immunohistochemically, the tubular structures without clear cells showed positive reactions to keratin, S-100, CEA and EMA. The tumor nest of clear cells reacted to only keratin. From these results and a review of the existing literature, it is thought that the clear-cell variant of mucoepidermoid carcinoma may be closely related to pleomorphic adenoma.