2092 A Rare Case of Primary Colonic Lymphoma Mimicking Metastatic Adenocarcinoma in a Patient With Ulcerative Colitis

Abstract

INTRODUCTION: Primary colorectal lymphoma (PCL) is uncommon and accounts for only 0.2-1% of all large intestine cancers. There is an increasing incidence in populations with Inflammatory bowel disease (IBD), Celiac disease, H. pylori and other autoimmune conditions. Here, we present a rare case of Ulcerative Colitis with primary Diffuse Large B Cell lymphoma (DLBCL) and liver metastasis. CASE DESCRIPTION/METHODS: Our patient is a 50 y/o male with left-sided ulcerative colitis presenting with a two- month history of severe left lower quadrant abdominal pain and constipation, without overt GI bleeding, diarrhea or weight loss. Examination was remarkable for left lower quadrant tenderness, without palpable mass. CT scan revealed multiple ill-defined liver masses concerning for metastasis with circumferential thickening in sigmoid colon with fat infiltration. Of note, patient had surveillance colonoscopy, few months prior to presentation which revealed marked erythema in the sigmoid colon, biopsies revealed acute on chronic inflammation without evidence of malignancy. Labs with normal CEA, AFP, CA 19- 9 levels. Repeat colonoscopy showed an ulcerated stricture with friable nodular mucosa in the sigmoid colon that was again biopsied in conjunction with biopsy of the liver lesions. Immunohistochemical staining of colon and liver lesions was positive for CD20 and negative for CK20, CK7 and CDX2, consistent with DLBCL. Patient was started on R-CHOP chemotherapy and is currently being monitored for response by Oncology. DISCUSSION: The risk of colorectal cancer significantly increases in IBD and surveillance is usually warranted. Although the suspicion of adenocarcinoma remains high in a UC patient with colonic mass and liver metastasis, PCL should also remain in the differential as correct pre-operative identification is crucial for the design of treatment. PCL is rare, with a male predominance in age 50-70 years and typically present with abdominal pain, lower GI bleeding, weight loss, palpable mass and rarely bowel obstruction. Diagnosis is aided by tissue biopsy and imaging. Multimodality approach involving both surgery and chemotherapy is the principal mode of treatment with radiotherapy in selected cases. Considering our patient’s clinical scenario, further speculations in routine CT scans to evaluate symptoms, alongside endoscopic surveillance for colorectal cancer in IBD, needs to be addressed.