Multinucleate giant cells in sublabial salivary gland tissue in Sjögren's syndrome. A diagnostic pitfall.

The presence of multinucleate giant cells in the sublabial salivary gland tissue in Sjögren's syndrome is an unusual phenomenon which can give rise to differential diagnostic problems. We found in 4 cases of 55 patients with Sjögren's syndrome multinucleate giant cells. In 2 of these 4 patients epimyoepithelial islands were also present. The combination of both multinucleate giant cells as epimyoepithelial islands can mimic the histological picture of a non- caseating granulomatous disease. To discriminate between an epimyoepithelial island and an epithelioid granuloma the immunoperoxidase technique with antibodies directed against muramidase appeared an useful tool. The epithelioid cells contain muramidase whereas the cells in the epimyoepithelial island do not contain this enzyme. Thus, multinucleate giant cells are a rare phenomenon in Sjögren's syndrome, therefore restricting its diagnostic significance. When they occur in Sjögren's syndrome staining for muramidase can be of help to avoid a false positive diagnosis of diseases in which non- caseating granulomatous inflammation occur, such as in sarcoidosis.