S2220 A Solitary Extramedullary Plasmacytoma Found in the Sigmoid Colon

Abstract

Introduction: Plasmacytomas are rare tumors made of a single line of plasma cells that can appear anywhere in the body, but the majority arise in the bone marrow. Extramedullary plasmacytomas (EMPs) represent less than 5% of cases, and only 5% of EMPs occur in the gastrointestinal (GI) tract. GI EMPs occur most commonly in the small intestine, followed by the stomach; colonic EMPs are rare. We present a case of a solitary extramedullary plasmacytoma found in the sigmoid colon on routine colonoscopy. Case Description/Methods: A 75-year-old female with a history of hypertension and diabetes presented for evaluation of sour taste in her mouth and epigastric pain, and also for average-risk colorectal cancer screening. Esophagogastroduodenoscopy showed Los Angeles Classification grade A esophagitis and patchy gastric erythema with Helicobacter pylori infection confirmed from random gastric biopsies. Colonoscopy showed an erythematous nodule in the sigmoid colon, and polypectomy was performed (Figure). Pathology showed plasma cell population with immunostaining that was overwhelmingly positive for IgG and kappa consistent with extraosseous plasmacytoma. A repeat colonoscopy was performed in 4 months which confirmed complete removal of the plasmacytoma. The patient was referred to a hematologist with evaluation pending. Discussion: Colonic EMPs are rare. Patients can either be asymptomatic or present with abdominal pain, melena, and hematochezia. Once confirmed on pathology, patients should undergo extensive work-up including a complete blood count, comprehensive metabolic panel, and positron emission tomography to assess for more extensive involvement. Radiation therapy is warranted if complete surgical resection is not achieved, and these patients must be monitored closely for signs and symptoms of multiple myeloma. It is crucial for gastroenterologists to understand the significance of this rare finding to facilitate a comprehensive evaluation.Figure 1.: An erythematous nodule in the sigmoid colon.