Carcinosarcoma of the parotid: investigating its biology with morphoproteomics.

Carcinosarcoma of the parotid is a rare biphasic malignant neoplasm comprised of both carcinomatous and sarcomatous components representing approximately 0.4% of all malignant salivary gland neoplasms. We report a case of a 55-year-old Caucasian man who presented with a progressively enlarging left facial mass. Histopathological evaluation of the tumoral tissue revealed a high grade, mixed epithelial and mesenchymal malignant tumor, most consistent with a carcinosarcoma of the parotid. Morphoproteomic analysis was performed and revealed expression of secreted protein acidic and rich in cysteine (SPARC); glioma-associated oncogen protein 2 (Gli2); and phosphorylated signal transducer and activator of transcription (p-STAT3 [Tyr705]) in the carcinomatous and malignant mesenchymal components. These aforementioned markers have been linked to the epithelial-mesenchymal transition in which epithelial cells lose their characteristics and phenotypically become mesenchymal cells. This finding allows us to further understand the biology of the 2 cellular components of the carcinosarcoma as having a monoclonal origin.