1557 Not Your Average Colon Cancer: Diffuse Large B-Cell Lymphoma in a Terminal Ileum Mass and Colon Polyp

Abstract

INTRODUCTION: Although the GI tract is a common site of extranodal non-Hodgkin lymphoma, primary ileocolonic lymphoma is rare among GI malignancies. Here, we report the case of a man presenting with abdominal pain diagnosed with diffuse large B-cell lymphoma (DLBCL) in his terminal ileum and sigmoid colon on colonoscopy. CASE DESCRIPTION/METHODS: A 72 year-old male with type 2 diabetes mellitus and recurrent UTIs presented with several weeks of abdominal pain and rectal bleeding. A colonoscopy 7 years prior showed diverticulosis. He had a 10 pack-year smoking history (quit 35 years prior). Family history was notable for a father with prostate cancer. Exam showed abdominal tenderness in the right lower quadrant. Laboratory work-up was only notable for ESR 25 and CRP 1.1. CT abdomen/pelvis demonstrated wall thickening in the cecum/ascending colon with surrounding inflammatory change and reactive adenopathy. Colonoscopy showed an ulcerated 2.0 × 1.8 cm mass in the terminal ileum, involving one-third of the lumen circumference (Figure 1). A 1.0 cm semi-pedunculated polyp was found in the sigmoid colon (Figure 2). Pathology of the ileal mass was consistent with DLBCL, non-germinal center B cell origin; pathology of the sigmoid polyp was tubular adenoma with large atypical lymphoid submucosal cells, suggestive of lymphatic involvement. DISCUSSION: The ileocolonic area is the least common site of primary GI lymphoma, accounting for only 0.3-0.5% of malignancies found there. Most patients present with abdominal pain, lower GI bleeding, or weight loss. GI lymphoma is more common in men, age 60-70s. Other risk factors are immunosuppression, chronic viral illness, H. Pylori, IBD, and Celiac disease. CT is the mainstay in diagnostic imaging. However, radiographic and endoscopic appearance cannot differentiate GI lymphoma from other malignancy; biopsy is the only way to confirm diagnosis. DLBCL is the most common subtype, with mantle cell and follicular lymphoma less prevalent. There is no standard treatment, although surgery is generally performed given risk of spontaneous perforation. Chemotherapy is often offered alone or adjuvantly as disease usually extends beyond local fields. Though our case has some typical features of GI lymphoma, ileocolonic involvement is very uncommon, and occurrence in multiple areas is rare, found in less than 10% of primary GI lymphomas. Thus, this case is unique, as the patient had an ileal mass as the primary site of DLBCL with a polyp in the sigmoid, suggesting lymphatic spread.