[Diagnosis and prognosis of salivary gland tumors. An interpretation of new revised WHO classification]

Abstract

An exact morphological classification of salivary gland tumours is necessary for international comparison of clinical tumour studies. The basis is formed by the TNM system for determining tumour stage ("staging") and the WHO classification as the underlying principle of identifying the pathohistological tumour state and cellular tumour differentiation ("grading"). The second, revised edition of the WHO classification of salivary gland tumours differs from the first in that the exact definition of a considerably greater number of tumour entities is given and in the consideration of additional factors concerning prognosis and therapy. In the present interpretation of salivary gland tumours, not only are solitary tumour entities defined, but new findings are also considered concerning immunohistochemical tumour markers, proliferation markers (Ki-67 resp. MIB 1, AgNORs, PC-NA), oncogenes and cell receptors as well as cytogenetic alterations as prognostic factors. In particular the new tumour entities of adenomas (myoepithelial adenoma, basal cell adenoma, canalicular adenoma) and carcinomas (acinic cell carcinoma, mucoepidermoid carcinoma, polymorphous low-grade adenocarcinoma, salivary duct carcinoma, myoepithelial carcinoma) are characterized. In addition, the tumour-like lesions and differential diagnostic aspects are mentioned and a general review about new prognostic factors is presented.