Pleomorphic adenoma is the most common tumor of the salivary glands. In the major salivary glands, the parotid gland is the most common site of this tumor, followed by the submandibular gland. Pleomorphic adenoma shows remarkable variation of histopathological characteristics and often contains mesenchymal components, including myxoid or chondroid tissues. We present a rare case of pleomorphic adenoma in the submandibular gland with remarkable bone formation. A 37-year-old Japanese man was referred to us because of a mass in the submandibular gland, measuring 70×60 mm. The mass had first been noticed more than 10 years previously and thereafter slowly increased in size. It was removed under general anesthesia, and the entire surgical specimen was processed for microscopic examination. The tumor was diagnosed to be a pleomorphic adenoma. Histologically, the main components were duct cells and sheets of tumor cells. In stromal regions, cartilage and remarkable bone formation were observed with myxomatous changes. The patient is presently doing well 10 years after surgery. We report the histopathological findings and describe the diagnostic images of this case.
