Marginal zone lymphoma: Associated autoimmunity and auto-immune disorders.

Large epidemiological studies have shown a consistent increased risk for developing lymphoma in the setting of autoimmune disorders (AID). It is known that this link appears to be stronger for some AID and certain non-Hodgkin lymphoma subtypes e.g. Sjögren's syndrome and extra-nodal marginal zone lymphoma of the salivary gland, and thyroid MALT lymphoma in a background of Hashimoto's thyroiditis. B and T-cell hyperactivity due to chronic antigenic stimulation and the consequent presence of acquired lymphoid tissue seems to play a key role in the pathogenesis of AI-related lymphomas. Advanced age at diagnosis, prolonged disease course and disease severity are thought to increase the risk of lymphoma development in AID patients. There is increasing evidence that AI-related lymphomas constitute a different spectrum of entities indicating a different pathobiology with specific clinical features and treatment implications. This chapter will provide a general overview on the epidemiological aspects of the NHL-AID association focussing on marginal zone lymphomas - one of the NHL subtypes mostly implicated in the synchronous/metachronous association with AID. We will review the possible biological mechanisms involved and the risk factors in each autoimmune condition related to this lymphoma.