COELIAC DISEASE Malignant lymphomas in coeliac disease: evidence of increased risks for lymphoma types other than enteropathy- type T cell lymphoma

Background: Numerous studies have reported on the association between coeliac disease and the otherwise uncommon enteropathy-type T cell lymphoma (ETTL). A systematic risk assessment of more prevalent lymphoma entities, such as B cell and non-intestinal lymphomas, in coeliac disease has not been performed. Aims: In light of the increasing number of patients diagnosed with coeliac disease and the unknown aetiology of malignant lymphomas, we aimed to estimate the distribution and risk of lymphoma subtypes in coeliac disease. Methods:We reviewed and reclassified 56 cases of incident malignant lymphomas occurring in a Swedish population based cohort of 11 650 patients hospitalised with coeliac disease. The observed numbers of lymphoma subtypes were compared with those expected in the Swedish population. Results: The majority (n = 32, 57%) of lymphomas in the cohort were not intestinal T cell lymphomas. Significantly increased risks were observed for B cell non-Hodgkin lymphoma (NHL) (standardised incidence ratio (SIR) 2.2 (95% confidence interval (CI) 1.2–3.6); 11 non-intestinal and five intestinal) and for lymphomas of non-intestinal origin (SIR 3.6 (95% CI 2.3–5.2), 11 B and 14 T cell). Furthermore, 44% of patients with B cell NHL had a history of other autoimmune/inflammatory diseases. The relative risks for T cell NHL (SIR 51 (95% CI 35–68); n = 37) and for primary gastrointestinal lymphomas (SIR 24 (95% CI 16– 34); five B and 25 T cell) were markedly increased, as anticipated. Conclusion: Most lymphomas complicating coeliac disease are indeed related to the disease and are not of the ETTL-type. There was a remarkable aggregation of autoimmune/inflammatory disorders, female sex, coeliac disease, and B cell lymphoma.