Lymphoid and myeloid proliferative disorders associated with inflammatory bowel disease: a clinicopathological study of 15 cases.

Lymphoproliferative disorder (LPD) can occur in patients with inflammatory bowel disease (IBD) such as ulcerative colitis (UC) and Crohn's disease (CD). On rare occasions, patients with IBD develop myeloid neoplasms; however, the frequency and clinicopathological features of IBD-associated lymphoid and myeloid proliferative disorder (LMPD) in Japanese patients are still unclear. In this study, we reviewed 2474 Japanese patients with IBD and found that LMPD occurred in 12 (0.5%) patients with UC (n = 7) or CD (n = 5). Together with an additional 3 cases, we analyzed a total of 15 cases of LMPD for clinicopathological and histological features. Based on the status of using immunosuppressants such as biologics and immunomodulators, Epstein-Barr virus (EBV) infection, and histopathology, the 15 cases were classified into Group I (high-grade LPD; n = 7), Group II (low-grade LPD; n = 5), and Group III (myeloid neoplasms; n = 3). Most patients in Group I were undergoing strong immunosuppressive therapy, and the LPD lesions corresponded to high-grade B-cell or T cell/natural killer cell lymphoma often with EBV infection. Discontinuation of immunosuppressive drugs alone did not resolve these LPDs; Group I patients required chemotherapy, and eventually 4 of them (57%) died of the tumor. Most cases in Group II were low-grade B-cell lymphoma without EBV infection and had an indolent clinical course with excellent prognosis. All patients in Group III developed acute myeloid leukemia (AML) during the course of CD. Two (67%) of these patients died of AML. Our study suggests that IBD-associated LMPD is very rare but can follow an aggressive clinical course.