Carcinosarcoma (True Malignant Mixed Tumor) of the Parotid Gland: A Report of a Case with Small Cell Carcinoma as the Carcinoma Component

ABSTRACT

True malignant mixed tumor (carcinosarcoma) of the salivary gland is an extremely rare tumor. By definition, it is a heterologous neoplasm that's composed of both malignant epithelial and mesenchymal components. We report here on a case of an 83 year old female patient with a parotid gland mass. Histologic examination showed a biphasic pattern of growth with both a poorly differentiated epithelial component and a sarcomatous spindle cell background. The immunohistochemical and ultrastructural findings support the diagnosis of a small cell neuroendocrine epithelial tumor and an undifferentiated malignant mesenchymal features. The histologic and ultrastructural features along with the immunohistochemical findings are presented. We also review the literature and we discuss the different opinions on the exact histogenesis of the true malignant mixed tumor of the salivary gland. To the best of our knowledge, this histological pattern has not been previously reported in the English medical literature.