63-year-old male patient with a past medical history of hypertension, obesity and dyslipidemia, retired from the textile industry of Pará de Minas, looked for medical assistance due to melena for 3 days with no other associated signs or symptoms. The first episode was 5 months earlier, for which he received no blood and was discharged after eight days of hospitalization. Previous history of acute pancreatitis in 2008 and bleeding from esophageal varices in 2012, as well as stenosis of the splenic vein and portal hypertension due to schistosomiasis.

Question:
According to the story and the image of the patient's colonoscopy, what is the most likely cause of melena?