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.