Pancreatosplenectomy and Spleen-Preserving Distal Pancreatectomy

Pancreatosplenectomy (pancreaticosplenectomy) or spleen-preserving distal pancreatectomy is performed to surgically treat pancreatic disease of the tail and body. Distal pancreatectomy involves surgical resection of the body and tail of the pancreas to the left of the superior mesenteric vein (SMV)–portal vein confluence, ^[1]  with or without splenectomy.

The choice of procedure depends upon the disease process, the characteristics of the lesion, and the surgeon's experience. Spleen-preserving distal pancreatectomy is reserved for chronic pancreatitis, proven benign pancreatic lesions and cysts, neuroendocrine tumors, and trauma.

Lesions in the body and tail of the pancreas become symptomatic as they enlarge and invade surrounding structures. However, with the increasing use of imaging studies, more incidental pancreatic lesions are discovered and diagnosed. Smaller lesions diagnosed at earlier stages are more amenable to surgical treatment.

Pancreatic neoplasms

Adenocarcinomas of the distal pancreas account for 15-25% of pancreatic adenocarcinomas. ^[2] Distal pancreatosplenectomy with lymphadenectomy is indicated for adenocarcinoma that is locally resectable without distant metastasis. Spleen-preserving distal pancreatectomy is contraindicated for malignant lesions of the distal pancreas.

Neuroendocrine tumors represent 2-4% of pancreatic tumors. ^[2] All neuroendocrine tumors have malignant potential and should be resected with curative intent.

Solid pseudopapillary tumors are evenly distributed throughout the pancreas, with 46-67% present in the body and tail. These tumors represent 0.9-2.5% of solid pancreatic tumors, with 82-93% of cases diagnosed in young women. ^[2] Curative resection should be attempted unless other contraindications are present.

Chronic pancreatitis

Chronic pancreatitis is defined as chronic and recurrent inflammation of the pancreas. ^[3]  Surgery is indicated for pain, pseudocysts, suspicion of malignancy, stenosis of the middle to distal pancreatic duct, pancreatolithiasis, and stenosis of the celiac or mesenteric vessels. Intractable pain is the most common indication for distal pancreatectomy in chronic pancreatitis, with relief of symptoms in 31-90% patients. ^{[3, 4]}

Pancreatic cysts

Serous cystadenomas are typically benign and represent 20-40% of cystic pancreatic tumors; they do need resection unless a large tumor is causing obstructive symptoms. ^[5] Mucinous tumors have malignant potential and account for 20-40% of cystic tumors. ^[5] Resection is indicated in symptomatic enlarging cysts larger than 2 cm. Intraductal papillary mucinous tumor is believed to follow the adenoma-carcinoma sequence and should be resected with curative intent.

Because of their similarities in appearance on diagnostic imaging, pancreatic pseudocysts and cystic tumors may be distinguished by means of endoscopic ultrasonography (EUS) with fine-needle aspiration (FNA). Findings suggestive of malignancy include mucin, mucin-secreting cells, or a high carcinoembryonic antigen (CEA) level in the cyst fluid. ^[5]

Symptomatic or enlarging pancreatic pseudocysts in the tail fo the pancreas can be treated with distal pancreatectomy after the acute pancreatitis episode has resolved. However, pseudocysts are best treated with internal drainage procedures as opposed to resection.

Contraindications for distal pancreatosplenectomy and spleen-preserving distal pancreatectomy include the following:

• Metastatic disease
• Peritoneal carcinosis
• Vascular invasion
• Pancreatitis involving the entire pancreas

Anatomy

The pancreas, from Greek pan- ("all") and kreas ("flesh"), is a 12- to 15-cm-long J-shaped (like a hockey stick), soft, lobulated, retroperitoneal organ. It lies transversely, though a bit obliquely, on the posterior abdominal wall behind the stomach, across the lumbar (L1-2) spine (see the image below).

The head of the pancreas lies in the duodenal C loop in front of the inferior vena cava (IVC) and the left renal vein. The body and tail of the pancreas run obliquely upward to the left in front of the aorta and left kidney. The pancreatic neck is the arbitrary junction between the head and body of the pancreas. The narrow tip of the tail of the pancreas reaches the splenic hilum in the splenorenal (lienorenal) ligament.

For more information about the relevant anatomy, see Pancreas Anatomy.

Procedural planning

About 50% of patients with adenocarcinoma have locally-advanced unresectable disease, and 35% have distant metastasis at the time of diagnosis. ^[6] Therefore, staging laparoscopy is recommended prior to resection. Major vasculature involvement with the celiac root, peritoneal disease, and metastasis to the liver are contraindications for resection. ^[6]

There has not been a clear consensus regarding whether a laparoscopic or an open distal pancreatectomy should be performed. ^{[7, 8]} Laparoscopic distal pancreatectomy has advantages similar to other laparoscopic procedures, such as decreased intraoperative blood loss, fewer postoperative complications and decreased length of stay. ^{[9, 10]} (See Outcomes.) However, the general view has been that its applicability in the setting of malignancy requires further study. ^[11]

In 2020, guidelines on minimally invasive pancreas resection were released by the International Study Group on Minimally Invasive Pancreas Surgery (I-MIPS). ^[12]  According to these guidelines, minimally invasive distal pancreatectomy (MIDP) for benign and low-grade malignant tumors is to be considered over open distal pancreatectomy (ODP). MIDP for pancreatic ductal adenocarcinoma appears to be feasible, safe, and oncologically equivalent in experienced hands. As of the publication of the I-MIPS guidelines, no studies had specifically compared spleen-preserving MIDP with spleen-preserving ODP.

Complication prevention

When a splenectomy is planned with a distal pancreatectomy, meningococcal, pneumococcal, and Haemophilus influenzae type B vaccines should be given, ideally 2 weeks prior to the planned resection. Antibiotics, such as a second- or third-generation cephalosporin, should be administered 30 minutes prior to incision.

Multiple meta-analyses have demonstrated laparoscopic distal pancreatectomy to be safe with improved postoperative outcomes as compared with open resection. ^[13]  Jin et al found laparoscopic distal pancreatectomy to be associated with fewer blood transfusions, decreased blood loss, earlier oral intake, and fewer surgical-site infections (SSIs). ^[14]  There was no difference found in operative time or incidence of pancreatic fistula.

In a retrospective review by Kooby et al, ^[9]  short-term oncologic outcomes (node harvest, margin status) and long-term oncologic outcomes (survival) were comparable in open and laparoscopic distal pancreatectomy.

A review article by Borja-Cacho et al ^[15]  concluded that laparoscopic distal pancreatectomy had a similar morbidity to open pancreatectomy but had a decreased length of stay. This study concluded that laparoscopic distal pancreatectomy is a safe procedure that is appropriately used for benign pancreatic disease. A randomized prospective multicenter trial would be required for further comparison to determine whether laparoscopic distal pancreatectomy is appropriate in malignant pancreatic lesions.

In a randomized trial by Nigri et al, ^[16]  the conversion rate for laparoscopic to hand-assisted technique was 37%. The conversion rate for laparoscopic to open was 11%. Reasons for conversion included multiple intra-abdominal adhesions and hemorrhage.

Several studies have examined the feasibility of robotic distal pancreatectomy. Robotic procedures have the benefits of three-dimensional (3D) visualization and improved ergonomics to allow for fine dissection. The safety profile is similar to that for laparoscopic procedures; however, robotic distal pancreatectomy has been associated with increased cost and operating times.

Because of the varying outcomes in negative margins and lymph node yield, there has been a lack of consensus regarding the oncologic appropriateness of robotic distal pancreatectomy in malignancy. ^{[17, 18]}  The 2020 I-MIPS guidelines stated that both laparoscopic distal pancreatectomy and robotic distal pancreatectomy are safe and feasible and suggested that the choice of technique should be based on surgeons’ experience and local resources. ^[12]

Murakawa et al evaluated short- and long-term outcomes in 49 consecutive patients who underwent radical antegrade modular pancreatosplenectomy (RAMPS; see Technique) for pancreatic cancer. ^[19]  They reported a median operating time of 278 minutes (range, 140-625), a median intraoperative blood loss of 850 mL (range, 60-2790), an overall morbidity of 51.4%, and a mortality of 0%. After follow-up (median, 41.1 mo), the overall survival rate was 84.1% at 1 year and 38.6% at 3 years. Median overall survival was 22.6 months.

Abe et al studied 93 patients who underwent treatment of pancreas body and tail adenocarcinoma, comparing the results of standard retrograde pancreatosplenectomy (SRPS; n = 40) with those of RAMPS (n = 53). ^[20] In the RAMPS group, more lymph nodes were retrieved (28.4 ± 11.6 vs 20.7 ± 10.1), R0 resection was more frequent (90.5% vs 67.5%), there was less intraoperative bleeding (485.4 ± 63.3 mL vs 682.3 ± 72.8 mL), and operating time was shorter (267.3 ± 11.5 min vs 339.4 ± 13.2 min). 

Huo et al, in a meta-analysis of seven studies (N = 474) comparing RAMPS with SRPS in patients with left-side pancreatic cancer, found that the RAMPS group had a better overall survival than the SRPS group. ^[21] Significantly more lymph nodes were harvested in the RAMPS group, and this group also showed reductions in blood loss and recurrence rate. More high-quality clinical trials would be required to confirm these findings.