The risk of lymphoma has become a major issue concerning the management of patients with IBD [1–4]. Crohn’s disease and ulcerative colitis (UC), the two major forms of IBD, are chronic, disabling conditions with high morbidity rates but only a slightly increased rate of mortality compared with the general population [5]. IBD patients are at an increased risk of many cancers, and colon cancer has been regarded as the most important cause of excessive mortality in these patients [6,7]. Lymphomas have also been reported in IBD, with the majority of them occurring in the gastrointestinal tract, particularly in areas of active inflammation, indicating that chronic, active inflammation may increase the potential for malignant change in the bowel [8–10]. However, the association between IBD and lymphoma remains controversial – most population-based and referral center studies have not detected a significantly elevated risk of lymphoma in Crohn’s disease or UC patients [11]. The most robust and best-established risk factors for lymphoma are primary and acquired immunodeficiencies. Evidence that immunosuppressive medications may increase the incidence of lymphoma in transplant recipients has raised concerns regarding the use of these agents in the treatment of IBD. Furthermore, the emphasis of the medical management of IBD has shifted to earlier and more intensive use of immunosuppressive and biological agents. Recently, a French observational cohort study demonstrated an increased incidence of lymphoma in IBD patients receiving thiopurines [12], and reports of rapidly fatal hepatosplenic T cell lymphomas (HSTCL) in IBD patients treated with combination therapy further raise concerns about the risk:benefit balance of such therapies for the management of IBD [13].