Isolated Asymptomatic Colonic Plasmacytoma Presenting as a Polyp at Screening Colonoscopy

Isolated extramedullary plasmacytomas (IEMPs) are rare. Extramedullary plasmacytomas (EMPs) are uncommon and mostly occur in the nasopharynx or upper respiratory tract. EMP involvement of the gastrointestinal tract occurs in approximately 10% of cases, more often in the small bowel than the colon. Less than 40 cases of colonic IEMP have been reported. Asymptomatic colonic IEMPs are extremely rare with few reported cases. We present a 57-year-old asymptomatic man with a colonic IEMP found during screening colonoscopy. A sigmoid colon polyp was removed and diagnosed as a plasmacytoma. Further investigation revealed it to be an isolated lesion.