Intraductal papillary mucinous neoplasm of the pancreas with a bifid pancreatic duct
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- Tajima, Y., Adachi, T., Kuroki, T. et al. J Hepatobiliary Pancreat Surg (2009) 16: 865. doi:10.1007/s00534-009-0053-2
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A bifid pancreatic duct presenting a major bifurcation in the main pancreatic duct is one of the anatomical variations of the pancreatic ducts. We encountered a 71-year-old female with a 5-cm-diameter branch duct intraductal papillary mucinous neoplasm of the pancreas in whom preoperative endoscopic retrograde pancreatography demonstrated an anomalous bifurcation of the main pancreatic duct at the body of the pancreas. We performed a distal pancreatectomy, instead of a middle pancreatectomy, with a cutting line at the downstream pancreas to the duct bifurcation point. Intraoperative ultrasonography was useful to confirm the exact location of the pancreatic duct bifurcation as well as the tumor extension. The procedure resulted in a favorable outcome without any postoperative complications. Although a bifid pancreatic duct is an unusual anomalous condition, this case should alert surgeons to be aware of such anatomical variants when performing pancreatic resection, otherwise, incurable pancreatic complications may occur postoperatively.
KeywordsBifid pancreatic ductEndoscopic retrograde pancreatographyIntraductal papillary mucinous neoplasm of the pancreasIntraoperative ultrasonographyPancreatic resection
It is well known that various forms of developmental abnormalities of the pancreas, including pancreas divisum , annular pancreas , aberrant pancreas , and pancreatic hypoplasia , can occur. The wide application of endoscopic retrograde pancreatography (ERP) and recent advances in magnetic resonance (MR) cholangiopancreatography have allowed the identification of such anatomical variants involving the pancreatic duct system. A bifid pancreatic duct presenting a major bifurcation in the main pancreatic duct is one of the anatomical variations of the pancreatic ducts; however, this unusual condition could account for troublesome postoperative complications when pancreatic resections are indicated. This report describes a case with a branch duct intraductal papillary mucinous neoplasm (IPMN) of the pancreas in where preoperative ERP demonstrated a bifid configuration of the main pancreatic duct in the body of the pancreas.
A 71-year-old female was admitted to our hospital in May 2007 for further investigation of a cystic tumor in the body of the pancreas. Approximately 15 years previously, the patient noticed occasional mild back pain, and a subsequent computed tomography (CT) examination of the abdomen revealed a cystic tumor, measuring 1 cm in diameter, in the body of the pancreas. Thereafter, she was followed up at an outside hospital. In January 2003, the cystic tumor of the pancreas had enlarged to 3 cm in diameter and the follow-up was continued. Recently, the patient began to suffer from back pain after meals and therefore was referred to this hospital.
The anatomical variants of the pancreas are grossly classified into three types  according to the embryological developmental aspects: (1) migration variants (annular pancreas and aberrant pancreas), (2) fusion variants (pancreas divisum and functional divisum), and (3) duplication variants (number variants and form variants). The bifid pancreatic duct is categorized as a number variant of a duplication anomaly. The pancreas develops from the dorsal and ventral elements arising from the foregut, which normally fuse with each other during the second month of the embryonic development. The ventral pancreatic bud gives rise to a portion of the pancreatic head and to the uncinate process, while the rest of the pancreatic gland develops from the dorsal pancreatic bud [6, 7]. The ventral bud is initially bilobed and the bilobed configuration eventually regresses in most individuals, although a remnant may persist and possibly cause anomalies or variants of the uncinate branches as well as aberrant pancreatic tissue in the gut . The dorsal pancreatic element may also be bilobed, thus possibly accounting for the anomalous bifurcation in the main pancreatic duct .
Among the various anatomical variants of the pancreatic duct system, the bifid pancreatic duct is a relatively rare condition especially in adults. A large series of ERP investigation demonstrated the frequency of this anomalous pancreatic duct to be 0.9–2.7% [10, 11]. The clinical significance of the bifid pancreatic duct, including the development of pancreatic tumors as seen in the present case, still remains unclear. Bang et al.  as well as Uomo et al.  demonstrated no significant relationship between various pancreatic duct anomalies and pancreaticobiliary diseases or clinical conditions. However, anomalies of the pancreatic duct system, including the bifid pancreatic duct, could present as troublesome problems when pancreatic resections are indicated [12, 13]. In the present case, preoperative ERP findings provided useful information for understanding the configuration of the bifid pancreatic duct as well as the pancreatic IPMN and for planning the optimal treatment strategy. Although branch duct IPMNs can be candidates for limited pancreatectomy [14, 15], a distal pancreatectomy was therefore performed instead of a middle pancreatectomy, with a cutting line at the pancreas downstream of the duct bifurcation point to avoid postoperative serious pancreatic complications, because the bifid secondary pancreatic duct appeared to be too small in diameter to anastomose appropriately without postoperative pancreatic leakage or too large in its drainage area to ligate and sacrifice. IOUS was useful for confirming the exact location of the pancreatic duct bifurcation as well as the tumor extension and also for determining the appropriate transection line for the pancreas. Ohkubo et al.  demonstrated the efficacy of IOUS and IOUS-guided pancreatography in performing a successful pancreaticoduodenectomy in a patient with a bifid pancreatic duct associated with carcinoma of the duodenal papilla. On the other hand, Yoshida et al.  reported a pancreaticojejunostomy with double duct-to-mucosa anastomotic technique after a pylorus-preserving pancreaticoduodenectomy for chronic pancreatitis with a bifid pancreatic duct.
Although an anomalous bifurcation of the main pancreatic duct is an unusual anatomical disorder, a lack of knowledge regarding the possible presence of such pancreatic duct anomalies could lead to incurable postoperative pancreatic complications, including pancreatic leakage and obstructive pancreatitis. The preoperative evaluation as well as intraoperative assessment of the pancreatic duct system is therefore important when performing pancreatic resections in patients associated with pancreatic duct anomalies. ERP should be the confirmative modality for diagnosis and treatment of these patients, even though MR cholangiopancreatography has emerged as an effective noninvasive alternative procedure.