Secondary tumours in Sjögren's syndrome

The frequent association of Sjögren's syndrome (SS) with non-Hodgkin's B cell lymphoma (NHL) provides an example of the interplay of systemic autoimmunity and lymphoproliferative diseases, and an opportunity to study the pathogenetic steps of lymphomagenesis. NHL develops in approximately 5% of SS patients. Parotidomegaly, lymphadenopathy, inflammatory neuropathy and vasculitis have been found to be predictive of the development of lymphoma. A subsequent NHL is also heralded by the appearance of cryoglobulinaemia and serum or urinary monoclonal proteins. The typical histological type of NHL in SS is a low-grade extranodal marginal zone B cell lymphoma. The authors discuss the proposed key immunopathologic steps of lymphomagenesis in SS in detail. Recent results indicating the pathogenetic role of ectopic germinal centre formation in the involved exocrine glands, the potential importance of an antigen-driven clonal proliferation of autoreactive B-lymphocytes, the proposed role of the B-lymphocyte activating factor (BAFF) and of further cytokines and, finally, the changes of the chemokine milieu at the site of lymphoma development are highlighted.