DIFFUSE COLONIC MANTLE CELL LYMPHOMA IN A PATIENT WITH PRESUMED ULCERATIVE-COLITIS - DETECTION OF A PRECURSOR MONOCLONAL LYMPHOID POPULATION USING POLYMERASE CHAIN-REACTION AND IMMUNOHISTOCHEMISTRY

Primary lymphoma of the colon, a rare and typically late complication of ulcerative colitis, exhibits high-grade morphology and behavior whe n it occurs. Recently, several reports of colonic lymphoma masqueradin g as ulcerative colitis have been described. These previous reports de scribed inflammatory mucosal changes typical of ulcerative colitis as being present in superficial biopsies, leading to the initial diagnosi s of ulcerative colitis; however, further workup resulted in a diagnos is of primary colonic lymphoma within several months in these cases, a nd all symptoms and mucosal changes resolved after treatment of the ly mphoma. Herein we report a case of mantle cell lymphoma arising in the colon and rectum in a 71-year-old woman with a 4-year history of ulce rative colitis. Immunoglobulin heavy-chain gene rearrangements were de tected using the polymerase chain reaction procedure in fixed tissue i n the lymphoma as well as in a prior resection specimen that histologi cally appeared to show only changes of severe ulcerative colitis. This finding suggests that an indolent lymphoid proliferation may have bee n the underlying disease in this patient and raises questions about th e role of colonic lymphoma in causing mucosal injury.