Mucoepidermoid carcinoma of salivary glands.

We reviewed the pathologic slides and clinical data of 44 patients with mucoepidermoid carcinomas of major and minor salivary glands. There were 14 well-differentiated, 20 intermediate, and ten poorly differentiated tumors. Two tumors appeared to have only expansive growth. All of the others were invasive, and we identified two patterns of invasion: broad pushing borders and infiltrative permeation. Infiltrative permeation was seen in 13 of 34 well-differentiated and intermediate tumors of which four (31%) metastasized, and in eight of ten poorly differentiated tumors of which five (63%) metastasized. Six of the nine patients with metastases died of carcinoma. Three patients who died with well-differentiated or intermediate tumors survived 10.5 years after diagnosis. Three patients died of poorly differentiated carcinoma less than one year after diagnosis. No patient died of local disease only, and no tumor with a broad pushing border metastasized. Size of tumor, site of origin, tumor cell mitotic rate, and age and sex of the patient had little, if any, effect on prognosis. A combination of tumor differentiation and pattern of invasion were the most useful factors in predicting carcinoma behavior.