Scintiscanning of mucoepidermoid tumor of the parotid gland.

99m Tc-O 4 and/or 67 Ga-citrate scintigraphies were preoperatively applied to 13 cases of parotid mucoepidermoid tumor. The resected specimens were histopathologically subdivided into three types: well (6 cases), moderately (one case), and poorly differentiated (6 cases). As the other parotid neoplasms except adenolymphoma and oxyphilic adenoma, all poorly differentiated tumors showed focal defect image in 99m Tc-O 4 scintiscanning (4/4). They indicated a focal hot image in 67 Ga-citrate scanning at a high rate (4/6). Otherwise, well differentiated tumors were scarcely pointed out in cold image and were usually indicated as a symmetrical image (5/6) in 99m Tc-O 4 scanning. None of them showed a focal hot image in 67 Ga-citrate scanning, but two cases indicated diffuse increased uptake and another case showed a focal defect image. The clinical prognosis of mucoepidermoid tumors is extremely correlated to the degree of cell differentiation in our prospective study. For that reason, the therapeutic method should be carefully selected in the tumors suspected of low grade malignancy. Our study suggests that RI ( 99m Tc-O 4 and 67 Ga-citrate) scintigraphy is helpful in evaluating the malignancy grade of mucoepidermoid tumors.