Undifferentiated Tumours of Salivary Glands: Immunocytochemical Investigations and Differential Diagnosis of 22 Cases

Abstract

22 undifferentiated tumours of the Salivary Gland Register (University of Hamburg) were studied by conventional light microscopical and immunocytochemical methods to elucidate the heterogeneity of this tumour group. The following observations were made in this collective: 18 tumours displayed one or more markers for the epithelial character and were classified as carcinomas. 10 carcinomas were considered as primary ones and 8 were considered as secondary ones (metastatic or invasive "per continuitatem"). Primary carcinomas were subclassified as poorly differentiated variants of a distinctive type of salivary gland tumours, as follows: 6 cases of carcinoma in pleomorphic adenoma, and one case each of mucoepidermoid tumour, adenocarcinoma, salivary duct carcinoma and epidermoid carcinoma. Secondary carcinomas were subclassified as follows: 3 epidermoid carcinomas, 3 nasopharyngeal carcinomas and 2 bronchial carcinomas. One tumour positive for S-100 protein and NSE (Neuron-specific enolase) was classified as a metastatic melanoma. Another tumour positive for vimentin and actin was classified as a rhabdomyosarcoma of the periglandular tissue. Two tumours lacked any markers studied here and were regarded as a malignant paraganglioma and an undifferentiated lymphoma, respectively. The differential diagnosis of the undifferentiated tumours of salivary glands and the special problems of this tumour group are discussed.