Duodenal Mass Detected on the Screening Endoscopy

A 55-year-old woman visited the outpatient clinic to evaluate further a duodenal mass detected on the screening endoscopy.The patient complained an intermittent melena, and initial laboratory results showed microcytic hypochromic anemia (Hgb 10.0 g/dL reference 12.0-16.0g/dL, MCV 71.9 fL reference 79.0-95.0fL, MCHC 29.7 g/dL reference 32.0-36.0g/dL, and RDW 16.9% reference 11.5%-14.5%).On the abdomen computed tomography, about 2.7 cm-sized fat-containing enhancing mass was found in the duodenum (Fig. 1A).On the magnetic resonance imaging, the duodenal mass originated from the distal antrum (Fig. 1B).Endoscopy revealed a 2.5 cm-sized pedunculated hyperemic polyp that originated from the greater curvature of the pyloric ring (Fig. 1C).The head of the polyp was located at the bulb of the duodenum and was hyperemic with a spontaneously oozing hemorrhage (Fig. 1D).What is the most likely diagnosis?