A case of carcinoma in pleomorphic adenoma of the upper lip.

A 49-year-old man was admitted to the First Department of oral and Maxillofacial Surgery, Tokyo Dental College Hospital, because of a painless swelling (19 × 22 × 10 mm) of the left side of the upper lip. Cytopathologically, the lesion was suspected to be a benigh salivary gland tumor. Under local anesthesia, the tumor, including the surrounding normal tissue, was resected. The histopathological diagnosis was carcinoma in pleomorphic adenoma, because most of the lesion showed a structure typical of pleomorphic adenoma and consisted of several sizes of duct-like cells. However, malignant epithelial cells were also found. There has been no evidence of recurrence as of 6 months after the operation.In this patient, the diagnosis of a salivary gland tumor was difficult, especially before the operation. The outcome suggested that resection including the surrounding normal tissue should be performed, even the lesion is suspected to be a benign tumor.