The Malignancy of Mixed Tumors of the Parotid Gland

Abstract

Sixty-four benign mixed tumors and “carcinoma in mixed tumor” cases were treated in this hospital in 1952–1964. The material was reclassified from a total of 119 various parotid tumors treated. The histopathology was correlated with the clinical history, mode of treatment, 5-year follow-up and the number of recurrences. The criteria set forth by Eneroth and colleagues for the diagnosis of “carcinoma in pleomorphic adenoma” were strictly followed in the classification of mixed tumors. The results showed that only these behaved in a malignant fashion and the rest of mixed tumors showed a benign course of disease. The number of recurrences was higher in the group of tumors with multiple nodules, otherwise no differences in the behaviour was noted as related to cellularity, cell atypism and mitotic frequency. Of the 6 patients with “carcinoma in mixed tumor” three had received irradiation therapy for a parotid tumor not surgically removed 8–24 years prior to present rapid enlargement. In a group of patients with a comparably long history of parotid enlargement due to benign mixed tumor, none was similarly treated before.