Department of Pathology, Medical University of the Americas, CanadaFulltext PDF
Oncocytes are large epithelial cells characterized by abundant eosinophilic granular cytoplasm containing excessive mitochondria. Mucoepidermoid Carcinoma (MEC) is the most common salivary gland malignancy (10% of all major gland tumors), most commonly found in the parotid gland. Oncocytic Mucoepidermoid Carcinoma (OMEC) is a very rare tumor found most commonly in the parotid gland. This was a case of oncocytic mucoepidermoid carcinoma in a 26 year old Vietnamese male. He initially presented with a painless mass over his left jaw. Biopsy pathology of the mass showed lesion cells with no high-grade features identified; complete excision was recommended for further classification. Microscopic examination showed an ill-defined infiltrative tumor composed predominantly of solid sheets and nests. The tumor cells were predominantly oncocytic characterized by abundant eosinophilic cytoplasm, round nuclei, and prominent nucleoli with focal pleomorphism. Scattered mucocytes were present. To aid in diagnosis, the following stains were done: CK5/6, CK7, CK14, p63, Ki-67, CK903, CK20, GCDFP, SOX10, Androgen receptor, GATA3, PAS-D, and mucicarmine. The stains CK5/6 and p63 were performed to identify oncocytes. PAS-D and mucicarmine were performed to identify mucin and mucous cells. An accurate diagnosis of OMEC can be made using a combination of histological evaluation and the appropriate immunostains and special stains. Equivocal staining results can be further evaluated for MAML2 translocation with RT-PCR or FISH.
Hung L. Oncocytic Mucoepidermoid Carcinoma: A Case Report. Ann Clin Case Rep. 2019; 4: 1687 .