Supplementary Material for: Two cases of portal annular pancreas in patients undergoing pancreaticoduodenectomy

Introduction: Portal annular pancreas (PAP) is a congenital anomaly resulting from aberrant fusion of the ventral and dorsal pancreatic buds around the portal vein (PV). PAP was classified into three types by Joseph et al., based on the location of the main pancreatic duct around the PV. The presence of PAP is important for the surgical procedure because it is associated with the postoperative pancreatic fistula. There are no standardized surgical procedures of resection and reconstruction for PAP. Case presentation: We report two cases of subtotal stomach-preserving pancreatoduodenectomy in patients with PAP. One case of PAP was discovered coincidentally intraoperatively, and the other case was diagnosed before surgery. The first case was an 84-year-old male patient who underwent surgery for distal bile duct cancer. PAP was noticed intraoperatively when the uncinate process of the pancreas was detached from behind the PV. The second case was an 84-year-old female patient who also underwent surgery for distal bile duct cancer. We recognized PAP from preoperative computed tomography images. In both cases, the ductal anatomy was consistent with type IIIA PAP, and the dorsal pancreas was resected using a stapling device. During the postoperative period, there was no clinically relevant postoperative pancreatic fistula. Conclusion: PAP is rarely encountered intraoperatively; however, it is important to recognize it before surgery and take it into consideration when deciding upon the procedures for resection and reconstruction.

引言：门静脉环胰（Portal annular pancreas, PAP）是一种先天性异常，由腹胰芽与背胰芽在门静脉（portal vein, PV）周围异常融合所致。约瑟夫等人根据主胰管环绕门静脉的位置，将PAP分为三型。PAP的存在对手术方案制定具有重要临床意义，因其与术后胰瘘的发生密切相关，目前尚无针对PAP的标准化切除与重建手术方案。

病例报告：本文报告2例合并PAP的保留胃次全胰十二指肠切除术病例。其中1例在术中意外发现PAP，另1例术前即已确诊。第一例为84岁男性患者，因远端胆管癌接受手术，术中在分离胰腺钩突与门静脉后方时发现PAP。第二例为84岁女性患者，同样因远端胆管癌接受手术，术前通过计算机断层扫描（CT）图像确诊PAP。两例患者的导管解剖结构均符合IIIA型PAP，且均使用吻合器切除背侧胰腺。术后随访期间，两例均未出现具有临床意义的术后胰瘘。

结论：术中偶遇PAP的情况较为罕见，但术前识别PAP并在制定切除与重建手术方案时予以充分考量，具有重要临床价值。