Plasmacytoid Myoepithelioma of the Palate with Rapid Growth: A Case Report

  Myoepitheliomas are benign tumors which account for less than 1% of all salivary gland tumors. In this article, we report the clinical, pathologic, and immunohistochemical features of plasmacytoid myoepithelioma of the hard palate in a 73-year-old man having a painless hard palate mass with progressive growth for one month who was admitted in Alzahra Hospital of Isfahan University of Medical Sciences. The patient underwent a complete surgical resection of the tumor. Light microscopy showed a nodule with sharp margins of large cells with plasmacytoid aspect presenting round eccentric nuclei and an abundant and homogenous eosinophilic cytoplasm arranged in sheets and groups separated by an abundant, loose, myxoid and hyalinized matrix. Immunohistochemistry was performed on formalin-fixed and paraffin-embedded tissue with a panel of immunohistochemical markers comprising cytokeratin (CK), vimentin, S100, actin and EMA. Tumor cells showed strong and diffuse positivity for S100 and also CK, vimentin, and actin, but confirming the myoepithelial origin of the tumor, EMA immunostaining was negative.