Hiroyuki Tadokoro

Management of branch duct-type intraductal papillary mucinous tumor of the pancreas based on magnetic resonance imaging

Background: We assessed the usefulness of magnetic resonance imaging (MRI) in identifying nonmalignant intraductal papillary mucinous tumors (IPMTs) of the pancreas.Methods: Thirty-three patients with branch duct-type IPMT diagnosed by endoscopic retrograde cholangiopancreatography were prospectively examined with magnetic resonance cholangiopancreatography followed by dynamic gadolinium-enhanced MRI examinations, and patients with no findings suggestive of malignancy, including a solid mass, mural nodules, a main pancreatic duct wider than 5 mm in diameter, and stenosis of the main pancreatic duct, were prospectively followed up with sequential MRI examinations once or twice a year.Results: Twenty-six (79%) patients showed no findings suggestive of malignancy in the initial MRI examination. The diameter (mean ± standard error) of the main pancreatic duct was 3.9 ± 0.7 mm and that of the ectatic branch pancreatic duct was 36.0 ± 9.1 mm. Twenty-three patients were prospectively followed for more than 36 months and 22 of them showed no findings suggestive of malignancy during follow-up periods ranging from 39 to 77 months (mean = 55 months).Conclusion: MRI was useful to identify nonmalignant IPMTs of the branch duct type, and close follow-up observation with serial MRI examinations may be appropriate in the management of such patients.

Development and Congenital Anomalies of the Pancreas

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.

Persistence of the Left Part of the Ventral Pancreas May Cause Congenital Biliary Dilatation

Introduction Congenital biliary dilatation (CBD) is a congenital anomaly by which pancreaticobiliary maljunction (PBMJ) is accompanied in most patients. The etiology of these conditions is unknown. Aims To clarify the pattern of fusion between the ventral and dorsal parts of the pancreas. Methodology We examined the pancreases from five patients who had PBMJ with or without CBD and five control subjects, and we detected pancreatic polypeptide (PP) immunohistochemically. Results In cases of CBD, the pancreatic head was huge, while the uncinate process was undetectable. The dorsal portion of the head was formed by the ventral pancreas macroscopically. It was divided into PP-rich and PP-poor portions immunohistochemically. In cases of PBMJ without CBD, the uncinate process was relatively small. The PP-rich portion (ventral pancreas) was situated obliquely dorsal to the PP-poor portion (dorsal pancreas). Conclusions In case of CBD, the PP-rich and PP-poor portions of the ventral pancreas may be derived from the right and left parts of the ventral primordia, respectively. CBD may occur when the remnant of the left part of the ventral primordium prevents normal recanalization of the common bile duct, resulting in dilatation of the duct. In cases of PBMJ without CBD, PBMJ without CBD may be caused by abnormal fusion between the ventral and dorsal primordia.

Unusual fusion between ventral and dorsal primordia causes anomalous pancreaticobiliary junction

Anomalous pancreaticobiliary junction (APBJ) is a congenital anomaly in which the pancreatic duct joins the common bile duct proximal to the sphincter of Oddi. Anatomical and immunohistochemical examination of the pancreas with APBJ has rarely been performed. A 72‐year‐old woman with gallbladder cancer and APBJ died of respiratory failure. Macroscopic features of the pancreas were examined in detail. Immunohistochemistry using anti‐pancreatic polypeptide (anti‐PP) antibody was done to discriminate ventral and dorsal pancreas. Macroscopically the inferior part of the head of the pancreas was smaller than normal. The posterior surface of the head was obliquely grooved. Part of the pancreatic head protruded into the posterior side of the pancreatic head. A PP‐rich region was located in the superioposterior position of the pancreas head. Considering the relationship between the ventral and dorsal pancreas, it was inferred that the ventral primordium could obliquely fuse with the dorsal primordium during embryological development. As a result, APBJ occurs through an abnormal fusion between ventral and dorsal primordia.

Occult Pancreatobiliary Reflux and Associated Mucosal Changes of the Gallbladder

Occult Pancreatobiliary Reflux and Associated Mucosal Changes of the Gallbladder Jin Kan Sai, Masafumi Suyama, Yoshihiro Kubokawa, Hiroyuki Tadokoro, Nobuhiro Sato Purpose: To investigate pancreatobiliary reflux in individuals with a normal pancreatobiliary junction and assoicated mucosal changes of the gallbladder. Methods: A total of 108 patients, who had diffuse thickness of the gallbladder wall detected by ultrasonography and normal pancreatobiliary junction on ERCP, were examined for their pathological findings and biliary amylase levels. Results: Nine patients showed biliary amylase levels more than 10,000 IU/L, in whom 4 patients had carcinoma, 2 patients had dysplasia, and 2 patients had hyperplasia of the gallbladder. In contrast, none of the patients with biliary amylase levels less than 1,000 IU/L, had dysplasia nor hyperplasia of the gallblader. Conclustion: Pancreatobiliary reflux can occur in patients with a normal pancreatobiliary junction and induce cancerous and pre-cancerous lesion of the gallbladder.