Myoepithelial carcinoma of the parotid gland metastatic to the kidney: case report and review of the literature.

Myoepithelial carcinoma is a rare locally aggressive malignant neoplasm of the salivary glands. The tumor is composed almost exclusively of tumor cells with myoepithelial differentiation and characterized by infiltrative growth and potential for distant metastasis. Tumor cells often display morphologic heterogeneity with a wide range of cytomorphologic features, such as epithelioid, plasmacytoid, spindle, and clear cell types, making its recognition challenging. Only limited reports on its metastatic behavior are available in the literature. We describe a case of metastatic myoepithelial carcinoma of the kidney from the parotid gland diagnosed by computed tomography guided fine-needle aspiration biopsy. Immunochemical studies are important to confirm myoepithelial differentiation of the tumor cells. Knowledge of the clinical history, radiographic characterization, and morphological correlation with the primary tumor are emphasized.