Management of portal annular pancreas during laparoscopic pancreaticoduodenectomy.

Portal annular pancreas (PAP) is a pancreatic congenital anomaly consisting of pancreatic parenchyma encircling the portal vein and/or the superior mesenteric vein. It has been reported that the risk of developing a post-operative pancreatic fistula is higher following pancreaticoduodenectomy in patients with PAP, probably because of the possibility of leaving undrained a portion of pancreatic parenchyma during the reconstructive phase. Few manuscripts have reported a surgical technique of pancreaticoduodenectomy in case of PAP, herein we report the first case of a patient with PAP undergoing laparoscopic pancreaticoduodenectomy.

INTRODUCTION

Portal annular pancreas (PAP) is the rarest among pancreatic congenital anomalies, with a reported frequency around 1%,[1] and is the consequence of an aberrant fusion of the ventral and dorsal fetal pancreas on the right and left sides of portal vein (PV) and/or superior mesenteric vein (SMV), which are finally encircled by pancreatic parenchyma. PAP is asymptomatic; however, its recognition is crucial when a pancreaticoduodenectomy is planned, to minimise the risk of post-operative pancreatic fistula (POPF), reportedly more frequent in patients with PAP undergoing pancreatic surgery, and probably related to the possibility of leaving undrained an unrecognised portion of pancreatic parenchyma.[2] Previous articles have reported on pancreaticoduodenectomy performed in case of PAP, herein we describe the first case of laparoscopic pancreaticoduodenectomy (LPD) in a patient with PAP.

CASE REPORT

A 77-year-old affected by a 12-mm ampullary adenocarcinoma was referred to our centre. A pre-operative contrast-enhanced computed tomography-scan revealed the presence of pancreatic tissue encircling the PV [Figure 1a], depicting a PAP. A slight dilatation of the main pancreatic duct (MPD) and the accessory pancreatic duct (APD) was found, without communication between two ducts.

Figure 1

(a) Pre-operative computed tomography-scan axial image showing portal annular pancreas, with pancreatic tissue anterior (asterisk) and posterior (star) to the portal vein. (b) Laparoscopic view of the main pancreatic stump (asterisk) and pancreatic parenchyma (star) posterior to the portal vein, before (b) and after (c) the beginning of transection

The patient was scheduled for an LPD. Laparoscopic ultrasonography confirmed PAP and excluded a communication between MPD and APD. Following pancreatic neck transection and retroportal lamina dissection, pancreatic tissue posterior to the PV was identified [Figure 1b] and transected [Figure 1c]. The resulting two pancreatic stumps were dissected from the PV until they merged with each other, where a further parenchymal transection was performed, removing about 2 cm of parenchyma, finally obtaining a single pancreatic stump. This was mobilised for about 4 cm to perform a pancreatogastrostomy as previously described[3] [Figure 2a–d].

Figure 2

Schematic representation of parenchymal and pancreatic duct distribution with respect to the portal vein and superior mesenteric artery (a); two pancreatic stumps can be identified after transection of pancreatic parenchyma, anterior, and posterior to the portal vein (b); following pancreatic mobilisation at the left of portal vein and superior mesenteric artery, additional 2 cm of pancreatic parenchyma are resected to obtain a single pancreatic stump (c), which is further mobilized (for about 4 cm) for the pancreatogastrostomy (d)

Pathological examination confirmed an ampullary adenocarcinoma (pT1N0R0). The patient recovered without complications and was discharged on the post-operative day 18.

DISCUSSION

Two classifications have been proposed for PAP, based on pancreatic ducts anatomy and their relation with PV/SMV[4] and on the extension of ventral and dorsal pancreas fusion posterior to PV/SMV,[1] respectively. In the case, we describe, pancreatic parenchyma encircled the PV, configuring type B PAP according to the classification described by Karasaki et al. We identified an MPD anterior to the PV and an APD posterior, configuring a type 3 PAP, according to Joseph classification. However, such particular scenario was not considered a contraindication to LPD, and to the best of our knowledge, this is the first report on LPD in a patient with PAP.

During pancreaticoduodenectomy, the presence of PAP entails two modifications of the surgical procedure: (i) at least two transections of pancreatic parenchyma anterior and posterior to PV/SMV, are required; (ii) two resulting pancreatic stumps need to be taken into account for pancreatico-intestinal reconstruction. Previous reports have highlighted the importance of a clear assessment of pancreatic duct anatomy in patients with PAP to guarantee a proper drainage of every pancreatic segment. A previous report[5] showed that, when an intrapancreatic communication between two pancreatic ducts at the left of PV/SMV is found, it is possible to ligate the retroportal duct, while maintaining the drainage of the gland through the anteportal one. In the case, we report a clear communication between MPD and APD was not identified, thus the overmentioned solution was not feasible.

In addition, at our centre, pancreatico-intestinal continuity during LPD is routinely restored through a double purse-string pancreaticogastrostomy. Intraoperatively, we considered that a pancreatogastrostomy with two pancreatic stumps, though technically feasible, could be unsafe because it required a larger gastric wall incision to introduce the two stumps into the stomach, compared to the classic gastric incision performed for a single stump, thus jeopardising the anastomotic seal and increasing the risk of POPF. Consequently, we performed an additional parenchymal transection at the pancreatic body, to achieve a single pancreatic stump for pancreatic anastomosis.

CONCLUSION

We report the first case of LPD in a patient with PAP. Despite the reported association between PAP and POPF, we do not believe that PAP represents an absolute contraindication to LPD. The surgical technique we describe proved to be feasible and safe and may represent an option for the surgical management of patients with PAP undergoing LPD.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.