Epithelial-myoepithelial carcinoma of the parotid gland with adenoid cystic carcinoma-like features: a case report with immunohistochemical study.

A 69-year-old japanese female with epithelial myoepithelial carcinoma (EMC) in the parotid gland is reported. The tumor, 3.5 x 4.0 x 1.5 cm in size, was located in the left parotid gland. Histopathological examination of the surgically removed tumor revealed that it was composed of double-layered, tubule-like structures formed by inner eosinophilic ductal cells and outer clear cells, as well as solid clear cell nests. The unique histological finding of this tumor was that it had a cribriform-like arrangement of myoepithelial cells resembling an adenoid cystic carcinoma. On the other hand, the typical ductal and myoepithelial components of EMC showed the usual biphasic pattern and the expected immunophenotypes, with expression of low molecular weight cytokeratins, CAM 5.2 and EMA in the ductal part, and smooth muscle actin, S-100 protein, and vimentin in the myoepithelial component.