With interest in the hematologic and immunological-antitumor roles of the spleen, a spleen-preserving distal pancreatectomy (SPDP) has been proposed in the benign or borderline lesions of pancreas body and tail [1,2]. However, for pancreas body and tail cancer, splenectomy has been generally performed for oncologic safety (margin negative resection and effective clearance of the splenic hilar lymph nodes). Some authors suggested that splenectomy may not be necessary in well-selected pancreas neck and body cancer without tail invasion due to the low incidence of splenic hilar lymph node metastasis [3–5]. Nevertheless, no surgeon can omit splenectomy for pancreas neck or body cancer. However, if SPDP with borderline lesion is performed and pancreas cancer is diagnosed on postoperative pathologic finding, if it is R0 resection, the necessity of additional splenectomy remains questionable. The authors would like to report two clinical cases diagnosed as pancreatic cancer on postoperative pathology after SPDP and under observation without additional surgery. This case study was conducted after approval from the Pusan National University Hospital Clinical Trial Center Institutional Review Board (IRB number 2404-005-137). All the participants provided written informed consent, and clinical information was retrospectively obtained from the patients’ medical records.

In the first case, a 60-year-old woman with the pancreas cystic lesion increased from 3.5 cm in April 2011 to 5.5 cm in November 2013 on computed tomography (CT). The patient reported no clinical symptoms of illness. She also had a negative medical history and no family history of malignant tumors. The clinical examination showed no tenderness in her abdomen. No palpable mass was detected. Her general condition was good and tumor enzyme levels (carcinoembryonic antigen, carbohydrate antigen 19-9) were all normal findings. CT and magnetic resonance imaging (MRI) showed a mucinous cystic neoplasm in the pancreas body (Fig. 1). SPDP was performed, and regional lymph nodes enlargement was not observed in the operation field. Frozen section biopsy showed negative for malignancy. Based on the histological examination after surgery, the final diagnosis was a 0.2 cm sized adenocarcinoma originating from 4.5 cm mucinous cyst neoplasm (Fig. 2). Two jointly resected lymph nodes were confirmed pathologically in the specimen, and there were no signs of metastasis. In addition, no lymphovascular and perineural invasion was observed. The patient was discharged from the hospital on postoperative day 10 without postoperative complications and adjuvant chemotherapy was not performed. She was followed up as an outpatient for 8 years during which she had no recurrence. The second case was that of a 59-year-old woman who visited our hospital with pancreatic duct dilatation found after routine health screenings. In the past, she underwent postoperative radiotherapy for endometrial cancer, endoscopic mucosal resection for high-grade adenoma of the colon, and Mohs micrographic surgery for squamous cell carcinoma of face. The clinical examination showed no specific abnormalities and preoperative tumor enzyme levels were all normal. The pancreas duct at the pancreas neck portion showed an abrupt cutoff with soft tissue lesion on CT and MRI examinations. Clinically, it was diagnosed as pancreas cancer related to the main duct intraductal pancreas mucinous neoplasm (IPMN) (Fig. 3). Endoscopic ultrasonography-guided biopsy was performed and histologic examination revealed high-grade dysplasia. We performed a SPDP with lymph node dissection. The resected surgical margins were confirmed postoperatively to be negative for malignancy. Histopathology confirmed adenocarcinoma of 1.8 cm confined to the pancreas (Fig. 4). There was no lymphovascular, perineural invasion and metastasis in 18 retrieved lymph nodes. She was discharged on postoperative day 7 without postoperative complications and adjuvant chemotherapy was not also performed. She was also followed up as an outpatient for 2 years during which she had no recurrence.

Preservation of splenic artery and vein (Kimura,s technique) and ligation of splenic vessels (Warshaw,s technique) are usually performed for the standard operation of SPDP [1,2]. Negative surgical margins and adequate lymph node harvest are important in pancreatic cancer and are known to lead to long survival rates. Radical antegrade modular pancreatectomy has been reported to be superior to conventional distal pancreatectomy in achieving oncological results, but in this case, the Kimura method was performed because borderline lesions were suspected [6]. Additionally, Kimura SPDP may be preferred for benign pancreatic tumors and low-grade malignancies based on previous studies showing better re-sults than Warshaw,s method in reducing the risk of splenic infarction and gastric varices [7].

In the point of view of SPDP, splenectomy may be option for benign or low-grade malignant tumors including mucinous cystadenoma and IPMN. SPDP is a surgical method that has been reported the advantages of incidence of overall morbidity, including infectious complications and pancreatic fistula [8,9]. If SPDP is performed for a borderline lesion and cancer is diagnosed in postoperative pathologic result, the surgeon will be worried about whether to reoperation for splenectomy. In cases of pancreas body cancer without tail involvement, the frequency of splenic hilar lymph node metastasis has been reported to be 0% to 4.7% [3–5,10,11]. Moreover, an international cohort study reported that 47 patients (6.7%) out of total 700 patients who underwent distal pancreatectomy due to IPMN had lymph node metastasis. It was recently reported that SPDP is oncologically safe for patients without preoperative suspicion of malignancy [12].

From the perspective of pancreatic body cancer and tail cancer, lymph node metastasis is reported to be a factor affecting poor prognosis. Although the optimal lymph node anatomical region for distal pancreatectomy is still unclear, differences in metastatic lymph node sites have been observed in pancreatic body tail cancer where the tumor is confined to the left or right side of the left aortic margin, making it a viable option for organ preservation. There are reports that distal pancreatectomy may be a treatment option for selected patients based on tumor site [13]. In agreement with this report, if margin-negative resection and effective regional lymph node clearance are achieved, additional surgery for splenectomy for splenic hilar lymph node clearance may not be necessary. However, it is not recommended to omit splenectomy in case of clear pancreatic neck or body cancer unless verification through large-scale research for long-term outcomes and safety are preceded. In the first case, there was no retrieved lymph node, but the adenocarcinoma portion was too small (0.2 cm, T1aNx) and there was no lymphovascular invasion and perineural invasion, so we thought it was R0 resection. In the second case, there was no metastasis retrieved 18 lymph nodes. In spite of the adenocarcinoma portion was 1.8 cm, there was also no lymphovascular invasion and perineural invasion, so we considered it was R0 resection. Of course, reoperation and adjuvant chemotherapy were sufficiently explained to both patients, however, they refused. Both patients have 8- and 2-year disease-free survival. It is not yet possible to decide whether to omit splenectomy for pancreas neck or body cancer. However, if cancer is diagnosed after SPDP, additional splenectomy may not be necessary if it is R0 resection.