[Diagnostic pitfalls in benign and malignant salivary gland diseases. Their significance for prognosis and therapy].

Diagnostic pitfalls exist when benign salivary gland diseases are mistakenly classified as malignant, with consequences for treatment and prognosis. Examples are necrotizing sialometaplasia, metaplastic Warthin tumour and sclerosing polycystic sialadenopathy. The proper diagnosis is of eminent importance to distinguish cases of primary tumours that have developed in salivary glands or their lymph nodes from cases of extraglandular tumours with metastases in these glands or their nodes. In these cases clinical data and additional immunocytochemical methods are necessary to clarify the exact diagnosis, especially when the primary salivary gland tumours have a structure largely identical to the metastases (e.g. squamous cell carcinoma). Nasopharyngeal or cervical chordomas can be mistaken for pleomorphic adenoma or mucinous adenocarcinoma. The initial stage of malignant MALT lymphomas in association with Sjögren's syndrome demands identification of clonal rearrangement for therapeutic implication. The diagnostic criteria for proper classification are analysed in detail.