Understanding how the pancreas develops is essential to understand the pathogenesis of congenital pancreatic anomalies. Recent studies have shown the advantages of investigating the development of frogs, mice, and chickens for understanding early embryonic development of the pancreas and congenital anomalies, such as choledochal cysts, anomalous pancreaticobiliary junction, annular pancreas, and pancreas divisum. These anomalies arise from failure of complete rotation and fusion during embryogenesis. There are many theories in the etiology of congenital anomalies of the pancreas. We review pancreas development in humans and other vertebrates. In addition, we attempt to clarify how developmental failure is related to congenital pancreatic anomalies.

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Intraductal papillary epithelial neoplasms of the pancreatobiliary system (intraductal papillary neoplasm of the bile duct (IPNB) and intraductal papillary mucinous neoplasm (IPMN)) seem to share many clinicopathological features; however, IPNB has not been fully characterized. In order to understand the clinicopathological/immunohistochemical features of IPNB better, we compared 52 cases of IPNB with 42 cases of IPMNs with mural nodules. The IPNB cases were divided into two groups according to their histological similarity and according to five key histological findings. All IPNB and IPMN cases mainly affected middle-aged to elderly people, predominantly men. Mucin hypersecretion was less frequent in IPNB compared to IPMN. Group 2 IPNB more frequently had a higher histopathological grade and more extensive stromal invasion than IPMN. Group 1 IPNB and IPMN were further classified into four subtypes (gastric, intestinal, pancreatobiliary, and oncocytic). Although each subtype of IPNB and IPMN showed similar histology, the immunohistochemical results were different. The gastric type of IPNB was less frequently positive for CDX2, and intestinal IPNB was more frequently positive for MUC1 and less frequently positive for MUC2, MUC5AC, and CDX2 compared to each subtype of IPMN, respectively. In conclusion, IPNB and IPMN have some clinicopathological features in common, but mucin hypersecretion was less frequent both in IPNBs than in IPMN. Group 2 IPNB differed from IPMN in several parameters of tumor aggressiveness. Additional clinicopathological and molecular studies should be performed with respect to the subtypes of IPNB and IPMN.

Choledochal cysts are a congenital anomaly, and they show dilatation of the intra- or extrahepatic biliary tree. These cysts are uncommon in Western countries, but are not rare in Asian countries. Choledochal cysts are classified into five groups based on location or shape of the cysts. Types I and IV-A cysts are the most common types, which are associated with anomalous pancreaticobiliary junction (APBJ), but other cysts are not associated with APBJ. Types I and IV-A cysts appear to belong to a different category from other cysts embryologically. Type I and IV-A cysts accompany anomalies of the pancreas. Type I and IV-A cysts might occur when left ventral anlage persists, and with disturbed recanalization of the common bile duct. Endoscopic retrograde cholangiopancreatography is the gold standard for detecting APBJ, but it is an invasive procedure. Magnetic resonance cholangiopancreatography (MRCP) is a non-invasive imaging tool for detecting pancreatic and biliary trees. MRCP is the first-choice modality for diagnosing choledochal cysts and APBJ in pediatric patients. Cystoenterostomy is been performed because of high complication and mortality rates. Complete excision of the cysts with Roux-en-Y hepatojejunostomy is a standard procedure for choledochal cysts to prevent postoperative complications, including development of cancer. In this study, we review classification, pathogenesis, diagnosis, and treatment of types I and IV-A choledochal cysts

Limited resection of the pancreas is recommended for low-grade malignancies such as mucin-producing tumors. We propose a system of segmentation of the pancreas for the purposes of limited resection. The proposed system has an anatomical and embryological basis, and divides the pancreas into four segments, namely the anterior head, posterior head, body and tail. These segments are based on the conventional anatomical division of the pancreas, identification of the originating primordium, and distribution of the ventral and dorsal pancreas.