Salivary gland tumors in Malawi.

A study of 190 tumors of major and minor salivary glands seen in Malawi over a nine-year period showed an overall incidence rate similar to that in Western countries. However, submandibular and palatal tumors are relatively more common, parotid tumors more likely to be malignant, and submandibular tumors less likely to be malignant than in Western countries. No adenolymphomas were seen. Despite the long history given by many patients with pleomorphic adenomas, the rate of malignant change in these tumors was not high; the majority of carcinomas (16% of all tumors) appeared to rise de novo. Histologic features were similar to those of tumors from other countries but the occurrence of tyrosine crystals in 20% of the pleomorphic adenomas was unusual. Melanocyte colonization of a mucoepidermoid tumor and a carcinoma, both in the primary site and in metastases of a salivary gland tumor, has not been previously reported.