A case of duodenal malignancy or something else?

A 63-year-old man was hospitalized with abdominal pain and vomiting. Abdominal CT described gastric distention, identifying an abrupt decrease in caliber in the second portion of the duodenum (Fig.1A). Upper endoscopy revealed, in the transition from the bulb to the second duodenal portion, an edematous and diffusely congestive mucosa causing obstruction, not allowing passage of the gastroscope.