Middle segment-preserving pancreatectomy for metachronous intraductal papillary mucinous neoplasm after pancreatoduodenectomy: a case report

Discussion

Siassi et al. [7] first reported the procedure of middle segment-preserving pancreatectomy (MSPP) after distal pancreatectomy in 1999. Since then, several case reports have been published regarding the safety and effectiveness of MSPP as an alternative to TP. Some authors have recommended MSPP for patients with multicentric noninvasive lesions, such as IPMNs, and pancreatic metastases, because lymphadenectomy was not necessary [6, 8–10]. Recently, as a minimally invasive surgery, laparoscopy-assisted MSPP was also reported [11]. Cheng et al. [6] reviewed 22 patients who underwent MSPP and showed that the overall morbidity was 40.9% (9/22), especially pancreatic fistula was 22.7% (5/22) with no mortality. Thus, MSPP was a safe and feasible procedure, and it has come to be widely performed for selected patients.

Postoperative exocrine and endocrine insufficiency is a major concern in pancreatectomy. Okano et al. [12] analyzed 227 patients who underwent PD or DP to determine the relationship between pancreatic volume and the postoperative pancreatic function. A volume of the remnant pancreas <24.1 ml was the only independent predictive factor for postoperative exocrine insufficiency; therefore, they recommended pancreatic enzyme therapy for these patients. Cheng et al. [6] reported that exocrine insufficiency after MSPP developed in 6 of 22 (27.3%) with a median follow-up of 18 months. Similarly, several other reports have described the relationship between the remnant volume of the pancreas and the postoperative endocrine function [13, 14]. Kang et al. [15] analyzed 101 patients who underwent DP and reported that a resected pancreatic volume >25% was a risk factor for endocrine impairment. Cheng et al. [6] also reported that endocrine insufficiency after MSPP developed in 7 of 22 patients (31.8%). Therefore, with respect to preserving the pancreas, these findings indicated that MSPP allows patients to avoid exocrine and endocrine insufficiency after surgery. In the present case, the volume of the remnant pancreas was very small (10 ml), which is 18.9% of the total pancreas; thus, the risk of postoperative exocrine and endocrine insufficiency was expected to be very high. Fortunately, our patient has maintained exocrine and endocrine functions without any kind of medication for more than 3 years after the second surgery. While the reason for this favorable outcome remains unclear, we speculate several reasons. First, at the initial surgery, the pancreatic function in the pancreatic body and tail was preserved because the pancreas head tumor was IPMN and not pancreatic cancer, and obstructive pancreatitis had not developed. Second, the resected pancreas in the last surgery was atrophic, and little of the functioning pancreas volume was lost. Third, we preserved the blood supply and drainage as much as possible. These conditions might have contributed to the good maintenance of the exocrine and endocrine functions of the remnant pancreas.

In addition, several reports have indicated that splenectomy is one of the risk factors for postoperative endocrine sufficiency. Hutchins et al. [16] analyzed 90 patients who underwent DP for chronic pancreatitis and reported that the incidence of DM after DP was lower in patients without splenectomy than in those with splenectomy (43 vs 72%). Tang et al. [17] retrospectively reviewed 82 patients who underwent DP with splenectomy and 78 patients who underwent DP without splenectomy for benign and borderline malignant tumors. They showed that fewer patients with splenectomy developed postoperative DM in comparison to patients who were treated without splenectomy (2.5 vs 12.2%). Thus, in cases in which an oncologically curative resection can be maintained (such as in the present case), the spleen should be preserved to provide a favorable endocrine function after surgery.

The preservation of the splenic artery was very important. First, although there have been no reports of pancreatic ischemia after MSPP, the blood supply to the remnant pancreas should be evaluated before surgery [8, 18]. The pancreatic body is mainly supplied by the splenic artery. In fact, in the present case, several small vessels to the pancreas, which originated from the splenic artery, were observed by preoperative CT. Second, the splenic artery has also been reported to be responsible for the main blood supply to the remnant stomach after distal gastrectomy [19]. In our case, the preservation of these vessels enabled the prevention of total gastrectomy.