Pancreas body adenocarcinoma with some overlapping features of acute pancreatitis. It is important to feel comfortable distinguishing these two diagnoses, or at least knowing when to raise the alarm of a potential adenocarcinoma and need for further workup (generally short term follow up with MRCP or endoscopic ultrasound with CA 19-9). 

In this case, the upstream atrophy of the tail with ductal dilation and narrowing of the splenic vein is highly suggestive of adenocarcinoma despite some of the surrounding stranding, and this diagnosis was confirmed with an endoscopic biopsy.