A Rare Case of Primary Colonic Non-Hodgkin’s Diffuse Large B-Cell Lymphoma

Abstract

Introduction: Primary colonic lymphoma is a rare manifestation of colonic malignancy. We report a rare case of primary colonic non-Hodgkin’s diffuse large B-cell lymphoma (PCNHDLBL) presenting as a symptomatic rectal stricture in a patient with ulcerative colitis (UC), who was being treated with azathioprine and adalimumab. Case Report: A 66-year-old male with a 7-year history of UC treated with azathioprine for 5 years and adalimumab for 3 years presented with complaints of 4 weeks of frequent loose stools, bloody bowel movements, and lower abdominal pain while defecating. On labs, hemoglobin was 10.6 g/dL, and WBC and the metabolic panel were within normal limits. The stool was negative for Clostridium difficile. Flexible sigmoidoscopy revealed rectal polyps and a partially obstructing stricture 10 cm from the anal verge. Biopsies were taken for pathology. The colonoscope could not be advanced beyond the stricture. A CT of the abdomen and pelvis showed distal sigmoid and rectal wall thickening, as well as pericolonic fat stranding consistent with active inflammation. Pathology of the stricture was positive for PCNHDLBL. The patient declined colectomy and elected to undergo chemotherapy with rituximab, cyclophosphamide, hydroxydaunorubicin, oncovin, and prednisone (R-CHOP). Discussion: PCNHDLBL is a rare extranodal type of lymphoma of the gastrointestinal (GI) tract and makes up approximately <1% of colonic tumors. Of primary GI lymphomas, most are non-Hodgkin’s, and the colon is the third most common site of these tumors after the stomach and small bowel. These tumors most commonly present with nausea, abdominal discomfort, weight loss, and GI bleeding. They are most often diagnosed by endoscopic biopsy. Azathioprine and anti-tumor necrosis factor alpha (anti-TNF) medications are associated with an increased risk of lymphoma; however, recent data has concluded that inflammatory bowel disease itself is not an independent risk factor. Azathioprine, an immunomodulator, has been reported to increase the risk of developing lymphoma in patients with inflammatory bowel disease by as much as 4 times. Anti-TNF medications such as adalimumab are also associated with an increased risk of non-Hodgkin’s lymphoma, with an estimated incidence ratio of 3 compared with the background rate in the general population. Conclusion: Azathioprine and anti-TNF medications are associated with an increased risk of lymphoma and other malignancies. It is important for the gastroenterologist to discuss the increased risk of lymphoma with the patient before initiating therapy with azathioprine and/or anti-TNF medications.