Mucoepidermoid carcinoma arises from salivary gland excretory ducts and is characterized by squamous epithelioid cells, mucin-producing cells and intermediate-type cells. This tumor accounts for about 10% of salivary gland tumors, and frequently occurs in the parotid gland and minor salivary glands of the palate.
We report a case of mucoepidermoid carcinoma presenting with atypical pathological features that was especially difficult to diagnose. A movable tumor, the size of the tip of the little finger, was found in the left side of the soft palate region of an 80-year-old man. There was no spontaneous pain or tenderness on palpation. The clinical diagnosis was a malignant tumor, and tumor resection was performed under general anesthesia on October 4, 1999. The histopathological findings showed that the tumor consisted of two parts, one comprised of squamous epithelioid cells arranged in an insular fashion in a mass of collagen fibers, and the other comprised of squamous epithelioid cells and relatively large oncocyte-like cells with acidophilic cytoplasm in an islet-type configuration among inflammatory cells. These tumor cells appeared to be undifferentiated, but the presence of squamous epithelioid cells and mucicarmine positive cells led to a diagnosis of mucoepidermoid carcinoma, poorly differentiated type.