Diagnosis and Treatment of Parotid Tumor

Abstract

A group study of parotid tumors was conducted. An epidemiological study revealed that annual incidence of the disease is 1.76 per 100,000 people, and that 75% of the patients were treated by otolaryngologists. A histopathological study revealed that 23% of the tumors were malignant, and 55.4% were pleomorphic adenoma generally originating from the reserve cells of the secretory duct. This adenoma often invaded the surrounding capsule or proliferated irregularly like a malignant tumor, suggesting a possible cause of occasional postoperative recurrences. Patients with malignant tumors, such as mucoepidermoid tumor, adenoid cystic carcinoma and adenocarcinoma, showed varying clinical courses; therefore, these lesions should be subclassified from the point of view of prognosis. To differentiate benign from malignant preoperatively, clinical examination, different methods of imaging and needle biopsy were evaluated. By these tests a wrong diagnosis was made in about 15% of benign tumors and in about 20% of malignant. Among these, sialo-computer tomography was the most useful for localizing a tumor mass in the parotid. Parotidectomy with preservation of the facial nerve was indicated not only for benign tumors but also for malignancies of low grade extension and for mucoepidermoid or acinic cell tumors. In the majority of patients facial nerve paresis due to surgical injury subsided within three months when the nerve was not sectioned. Frey's syndrome occurred in the half of patients after operation. Combined treatment of surgery with irradiation and anticancer drugs was presumed to be useful for prevention of recurrence and metastasis in cancer. The crude five-year survival rate for patients with parotid carcinoma was 23%. Some patients with distance metastasis survived for a long time. © 1986, The Society of Practical Otolaryngology. All rights reserved.