Trans-abdominal ultrasound features of the newly named intraductal papillary neoplasm of the bile duct

Background: Intraductal papillary neoplasm of the bile duct (IPMN-B) is a rare cystic neoplasm of the liver. This study retrospectively reviewed a relatively large sample of IPMN-B cases for diagnostic clinical or trans-abdominal ultrasound features. Methods: The medical records of 20 pathologically confirmed IPMN-B cases were reviewed. Serum concentrations of carbohydrate antigen 19-9 (CA19-9), carcinoembryonic antigen (CEA), and alpha-fetoprotein (AFP) were evaluated, and images of conventional trans-abdominal ultrasound. According to the relationship between the hepatic mass and the dilated bile duct, we classified cases as type I-IV: I, non-tumor; II, asymmetrical; III, symmetrical; and IV, aneurismal dilation. The clinical and trans-abdominal ultrasound characteristics of these types were compared. Results: The clinical features were non-specific; only malignant cases showed CA19-9 or CEA elevation. Three, 9, 3, and 5 cases were types I, II, III, and IV, respectively, and the diameters of the dilated common bile ducts were 2.27 +/- 1.08, 1.82 +/- 0.79, 0.57 +/- 0.15, and 0.68 +/- 0.08 cm. The dilations of the common bile duct of types I and II were significantly larger than that of III and IV. Pathologically, 15, 3, and 2 cases were adenocarcinoma, benign, and two border adenomas. The pathological distribution among the four types differed significantly for all of the benign cases and 50% of the border adenomas were type I or II; types III and IV more aggressively progressed to adenocarcinoma. Conclusions: In patients with IPMN-B, the elevation of serum tumor markers may indicate malignant potential. The typical trans-abdominal ultrasound feature of IPMN-B was significant diffuse dilation of the intrahepatic and extrahepatic bile ducts, especially for benign cases. Some malignant cases only showed serious local bile duct dilation with IPMN. After exclusion of extrahepatic bile duct obstructive disease, IPMN-B should be suspected in patients with significant dilation of the bile duct.