A 25-year-old man was referred to our hospital with melena and low abdominal pain. Abdominal computed tomography showed an 8-cm enhancing mass near the ileocecal valve leading to intussusception (Fig. 1A). Colonoscopy identified a huge ulcerated mass protruding into the proximal ascending colon (Fig. 1B). Pathological examination revealed the proliferation of diffuse large discohesive polygonal cells having high nuclear/cytoplasmic ratio which were CD138-, CD38-, and Ki-67- (high expression, 90%) positive; and CD20-, CD3-, and cytokeratin-negative. Plasma cell neoplasm or plasmablastic lymphoma (PBL) was suspected. Serum and urine protein electrophoresis results were unremarkable. A right hemicolectomy was performed owing to risk of impending intestinal obstruction. The specimen showed an 8- × 6-cm fungating mass arising from the ileocecal valve. The cut surface of the mass showed intussusception into the ascending colon (Fig. 1C and 1D). The resected tumor cells were identical to the endoscopic biopsy cells and spread from the mucosa to the serosa (Fig. 2A-2E). The results were negative for serum human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV) in situ hybridization expression (Fig. 2F). The final diagnosis was PBL with plasmacytic differentiation. The patient is in remission after six EPOCH (etoposide, prednisolone, oncovin, cyclophosphamide, hydroxydaunorubicin) chemotherapy cycles.