Clear cell carcinoma, not otherwise specified （NOS）, is extremely rare in the salivary gland. This tumor is one of the new additions to the 2005 World Health Organization （WHO） classification of salivary gland tumors. We report a case of clear cell carcinoma, NOS in the buccal mucosa.
A 59-year-old woman visited a hospital because of a painless tumor in the left buccal mucosa. The tumor was elastic hard and was the size of the tip of the pinky. The clinical diagnosis was a fibroma, and the tumor was resected under local anesthesia. The histopathological diagnosis was clear cell carcinoma, NOS, and the surgical margin was positive. Half a month after the excision, the patient visited our hospital to treat the residual tumor. The tumor measured 8 mm in diameter, and was excised under general anesthesia. Histological examination revealed that the tumor consisted of small cellular nests with clear cells showing clear cytoplasm and polygonal nuclei. Tumor cells were negative for antibodies against S-100 protein, muscle actin, and Alcian blue. On the basis of these features, the tumor was diagnosed as a clear cell carcinoma, NOS. There has been no evidence of recurrence or metastasis as of 4 years after surgery.