The authors report the case of a 78-year old patient affected by multiple myeloma who develops acute pancreatitis and pseudoaneurysmal dilatation of the inferior pancreaticoduodenal artery causing erosion of the second portion of the duodenal wall and hematemesis. The authors focus first on the supposed etiological relationship between multiple myeloma and acute pancreatitis, and they assume that the therapeutic treatment for the bone marrow disease (bortezomib) may have triggered the pancreatic inflammatory response. They then analyze the pathogenesis of the vascular complication which seems to be related to the lytic action of pancreatic enzymes on the vessel wall which results in the formation of a pseudoaneurysm first and a pseudocyst then. The vascular complication was diagnosed by computed tomography (CT) thus avoiding selective angiography which was considered too invasive for the patient. The careful and conservative treatment of the complication has allowed for full healing of the cephalopancreatic region, in addition to avoiding surgery or embolization treatment of the pseudoaneurysm which is accompanied by a mortality rate as high as 50%.