抄録
We describe our experience with a case of carcinoma ex pleomorphic adenoma. A 54-year-old woman was referred to our hospital because of a painless mass of the left palate that had been present for 10 years. Clinical examination revealed a 20×18×12-mm well-defined, elastic soft mass in the left region of the soft palate. The preoperative incisional biopsy showed pleomorphic adenoma without a malignant component, but the removed tumor included small foci of salivary duct carcinoma within pleomorphic adenoma. After the histological diagnosis of pleomorphic adenoma from the biopsy, the lesion was excised under general anesthesia. Histopathological examination of the excised specimen revealed an encapsulated tumor composed of solid and duct-like proliferation with hyalinous and myxoid extracellular matrices like an incisional biopsy. However, small malignant areas were noticed within the tumor. The carcinomatous elements were composed of nests of cribriform patterns and ductal structures containing necrotic tissues in the lumen. These structures were comprised of large epithelial cells with eosinophilic cytoplasmic granules and enlarged hyperchromatic nuclei, and peripheral mono-layered flattened cells without atypia. The eosinophilic cells and peripheral flattened cells immunohistochemically demonstrated phenotypes of duct luminal cell and myoepithelial cell, respectively. Based on the histological and immunohistochemical findings, the malignant component was diagnosed as salivary duct carcinoma. The present tumor was finally diagnosed as carcinoma ex pleomorphic adenoma. No signs of recurrence have been observed 3 years after surgery.
