Pancreatic adenocarcinoma with atypical imaging features mimicking chronic pancreatitis in a dog

An 11-year-old intact female Pomeranian dog was referred for jaundice, anorexia, and vomiting. The blood analysis revealed increased alanine aminotransferase, alkaline phosphatase, and gamma-glutamyl transpeptidase. The serum canine pancreatic lipase immunoreactivity was within the normal reference range. The radiography revealed no significant findings. On ultrasound, the gallbladder was enlarged with a markedly distended common bile duct (CBD) measuring up to 6 mm in diameter. The pancreas had an irregular contour, a hypoechoic peripheral rim, multiple hyperechoic foci with acoustic shadowing, and showed increased echogenicity of the adjacent mesentery. Based on these results, an extrahepatic biliary obstruction secondary to the presumed chronic pancreatitis was diagnosed. The computed tomography (CT) images showed a hypoattenuating pancreatic parenchyma compared to the liver in the early phase, as well as multiple calcifications. A laparotomy was performed to reserve the patency of the CBD. The histopathological examination of the pancreas revealed exocrine pancreatic adenocarcinoma. While various appearances of exocrine pancreatic adenocarcinoma on CT have been reported in humans, CT features of pancreatic adenocarcinoma have not been well-established in dogs. The purpose of this report is to describe the atypical imaging features of pancreatic adenocarcinoma that are similar to those of chronic pancreatitis in a dog.