S1615 Primary Rectal Lymphoma: A Rare Entity of Lower Gastrointestinal Bleeding

Abstract

INTRODUCTION: Primary rectal lymphoma is an extremely rare gastrointestinal neoplasm. The diagnosis can be delayed with varied presentations depending on the site of the colonic involvement. We present a case of acute onset of hematochezia from primary diffuse large B-cell lymphoma at the rectum. CASE DESCRIPTION/METHODS: A 54-year-old Caucasian man who has sex with men presented with constipation for 3 weeks and rectal bleeding for one week. He reported rectal pain associated with having bowel movements and tenesmus. He denied fever, chills, night sweats, or weight loss. Physical examination was unremarkable. Laboratory showed WBC 11.1 K/MM3, Hb 14.6 g/dL, platelet count 325 K/MM3, and negative serum HIV screening. CT scan of the abdomen and pelvis revealed circumferential rectal wall thickening with mesorectal fat stranding and enlarged mesorectal lymph nodes (Figure 1). The patient underwent flexible sigmoidoscopy which demonstrated circumferential deep ulcerations, linear erosions, and loss of vascularity of mucosa from the anus to the recto-sigmoid colon up to 20 cm and hypertrophied anal papillae (Figure 2). Biopsy of the rectum up to 20 cm revealed diffused large B-cell lymphoma with germinal center origin. A whole-body PET-CT scan showed disease activity localized in the rectum. Bone marrow biopsy showed slightly hypocellular bone marrow but negative for lymphoma. He underwent R-CHOP chemotherapy and radiation with a good response. Repeat colonoscopy at 3 months after treatment did not show evidence of recurrence. Follow-up PET-CT and CT chest/abdomen/pelvis were without recurrence of the disease. He remains in remission for 15 months since the diagnosis. DISCUSSION: Gastrointestinal (GI) non-Hodgkin lymphoma accounts for 1-4% of primary GI neoplasms. The stomach is the most commonly involved site followed by the small intestine and colon. Primary colorectal lymphoma only accounts for 6-12% of GI non-Hodgkin lymphomas. Diffuse large B-cell lymphoma (DLBCL) is the most common histopathology. Symptoms are varied depending on the location of the disease. Rectal lymphoma can present with rectal bleeding and obstructive symptoms, for example, constipation, small stool caliber, or tenesmus, as in this case. DLBCL is sensitive to chemoradiation. The estimated median survival of patients with localized disease is approximately 23 months. A high index of suspicion is required to prevent delays in diagnosis.Figure 1.: CT scan of abdomen and pelvis showed circumferential wall thickening at the rectum (arrows).Figure 2.: Flexible sigmoidoscopy showed circumferential deep ulcerations, linear erosions, and loss of vascularity of mucosa at the rectum (A) and hypertrophied anal papillae in retroflection view (B).