Muco-Epidermoid Carcinomas of the Salivary Glands

It has been questioned whether there is a benign variety of muco-epidermoid carcinoma (M.E.C.) with histologically highly differentiated structures. to find out whether such a definitely benign variety really exists a histological investigation was made of 23 muco-epidermoid carcinomas with a malignant course. These 23 cases were selected from 124 which, after histological reclassifica-tion of 2 867 parotid, submandibular and palate tumours, were classified as M.E.C. in 7 of the 23 cases the histological study revealed highly or moderately differentiated structures, and in 3 cases the primary tumour as well as the lymph node metastases were undoubtedly very high differentiated. These morphologically benign structures in cases with a malignant course would contradict the existence of a benign variety of M.E.C, and consequently tumours with highly differentiated structures should be denoted as carcinomas in preference to the sometimes suggested term of muco-epidermoid tumour.