Solitary extramedullary plasmacytoma (SEP) is a rare tumor due to the monoclonal proliferation of plasma cells without bone marrow involvement. Plasmacytomas are frequently encountered in bone or soft tissue but rarely occur in the gastrointestinal (GI) tract. They can present with a multitude of symptoms depending on their site. This report describes a case of SEP diagnosed as a duodenal ulcer (DU) during esophagogastroduodenoscopy (EGD) for iron deficiency anemia.