1646 Primary Colorectal Diffuse Large B-Cell Lymphoma: A Rare Presentation of a Rare Colonic Neoplasm

Abstract

INTRODUCTION: Diffuse Large B Cell Lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma accounting for 25% of cases. Of those, only one third are found to have a primary extranodal source. While this is known to arise from the stomach, a colorectal primary site is exceedingly unique. We present the case of primary colonic DLBCL diagnosed in a patient admitted for hematochezia. CASE DESCRIPTION/METHODS: An 85-year-old female with coronary artery disease on aspirin and diverticulosis presented to the emergency room with acute hematochezia and left lower quadrant (LLQ) abdominal pain. She was hemodynamically stable with reproducible LLQ tenderness and rectal exam confirming bright red blood. Labs were pertinent for leukocytosis and hemoglobin of 12.1 g/dL down from a baseline of 14.4 g/dL. Contrasted abdominal CT revealed a 4.1 cm soft tissue mass in the ascending colon with extravasation of contrast consistent with active bleeding. Due to concern for a malignant bleeding etiology, interventional radiology performed CT angiography, but were unable to identify an active arterial source. The patient continued with hematochezia and was taken for urgent colonoscopy. Within the ascending colon, a 5cm non-obstructing, fibrous mass with central ulceration was identified and biopsied. Colorectal surgery was consulted; due to concern for recurrent bleeding a right hemicolectomy was performed the following day. Final pathologic diagnosis revealed primary colonic DLBCL with local lymph node involvement. PET/CT showed complete resection of disease and, through multidisciplinary shared decision making, further treatment or surveillance was not pursued. At follow up the patient is doing well without recurrent symptoms. DISCUSSION: Primary colorectal DLBCL accounts for less than 0.3% of all cancers involving the large intestine. While data is limited, the majority of patients are male between the 5th and 7th decades of life. Symptoms are nonspecific with few cases discovered due to overt bleeding. Endoscopic appearance is variable including mucosal nodularity, ulceration or a mass with or without ulceration, which can mimic adenocarcinoma. Due to the abundance of lymphoid tissue, most lesions involve the cecum and ileocecal valve. Diagnosis of primary colonic DLBCL can include local lymph node involvement, but distant nodal disease must be excluded. The mainstay of treatment is surgical resection with adjuvant chemotherapy, however, due to patient age and preference a conservative strategy was pursued.