Serous cyst adenoma of the pancreas: appraisal of active surgical strategy before it causes problems

Pancreatic serous cystic neoplasms with spontaneous hemorrhage in a young woman: A case report

INTRODUCTION

Pancreatic serous cystic neoplasm (SCN) is usually benign and is often managed using imaging surveillance if asymptomatic. It has a higher incidence in females but is rare in younger age groups. Acute hemorrhagic complications associated with SCN are infrequent. Whether asymptomatic SCN can cause acute hemorrhage, especially in women of childbearing age, is not well-established.

PRESENTATION OF CASE

A 30-year-old Japanese female, who was six months postpartum and under surveillance for asymptomatic pancreatic SCN, presented to the emergency department with gradually worsening left lateral abdominal pain. Regular ultrasound revealed no change in SCN size; however, no imaging surveillance had been conducted over the past two years. She had pain in the entire abdomen, which intensified around the navel and elicited guarding. Abdominal contrast-enhanced computed tomography revealed a cystic mass in the pancreatic tail with a contrast blush within the cyst and an adjacent retroperitoneal hematoma. Endovascular embolization was performed to control the hemorrhage. The patient had an uneventful medical recovery and was discharged five days after embolization. Five months after discharge, she underwent laparoscopic distal pancreatectomy and splenectomy as an elective surgery and was discharged uneventfully.

DISCUSSION

Even with periodic imaging surveillance, pancreatic SCN can suddenly cause spontaneous hemorrhage. Clinicians should be aware that pancreatic SCN can potentially cause life-threatening complications, including spontaneous hemorrhage.

CONCLUSION

We report a case of an unexpected complication with spontaneous hemorrhage in a young woman who was under imaging surveillance for pancreatic SCN. The patient was successfully treated with angioembolization and planned laparoscopic surgery.

Multi-Phase CT-Based Radiomics Nomogram for Discrimination Between Pancreatic Serous Cystic Neoplasm From Mucinous Cystic Neoplasm

Purpose

This study aimed to develop and verify a multi-phase (MP) computed tomography (CT)-based radiomics nomogram to differentiate pancreatic serous cystic neoplasms (SCNs) from mucinous cystic neoplasms (MCNs), and to compare the diagnostic efficacy of radiomics models for different phases of CT scans.

Materials and Methods

A total of 170 patients who underwent surgical resection between January 2011 and December 2018, with pathologically confirmed pancreatic cystic neoplasms (SCN=115, MCN=55) were included in this single-center retrospective study. Radiomics features were extracted from plain scan (PS), arterial phase (AP), and venous phase (VP) CT scans. Algorithms were performed to identify the optimal features to build a radiomics signature (Radscore) for each phase. All features from these three phases were analyzed to develop the MP-Radscore. A combined model comprised the MP-Radscore and imaging features from which a nomogram was developed. The accuracy of the nomogram was evaluated using receiver operating characteristic (ROC) curves, calibration tests, and decision curve analysis.

Results

For each scan phase, 1218 features were extracted, and the optimal ones were selected to construct the PS-Radscore (11 features), AP-Radscore (11 features), and VP-Radscore (12 features). The MP-Radscore (14 features) achieved better performance based on ROC curve analysis than any single phase did [area under the curve (AUC), training cohort: MP-Radscore 0.89, PS-Radscore 0.78, AP-Radscore 0.83, VP-Radscore 0.85; validation cohort: MP-Radscore 0.88, PS-Radscore 0.77, AP-Radscore 0.83, VP-Radscore 0.84]. The combination nomogram performance was excellent, surpassing those of all other nomograms in both the training cohort (AUC, 0.91) and validation cohort (AUC, 0.90). The nomogram also performed well in the calibration and decision curve analyses.

Conclusions

Radiomics for arterial and venous single-phase models outperformed the plain scan model. The combination nomogram that incorporated the MP-Radscore, tumor location, and cystic number had the best discriminatory performance and showed excellent accuracy for differentiating SCN from MCN.

Impact of pulmonary embolism on morbidity and mortality in patients undergoing pancreatic surgery

PURPOSE

Postoperative pulmonary embolism (PE) after pancreatic surgery is a potentially life-threatening complication. However, the magnitude of morbidity and mortality of PE is still uncertain. The present study aims to assess the incidence of PE after pancreatic surgery and analyze its impact on the outcome.

METHODS

We conducted a retrospective study including all patients who underwent pancreatic resections between 2005 and 2017. The development of PE was analyzed for a 90-day period following surgery. Risk factors were evaluated using regression models.

RESULTS

The study investigated 947 patients undergoing pancreatic surgery. Overall, 26 (2.7%) patients developed PE. The median body mass index (BMI) of patients with PE was significantly higher (28.1 kg/m² [24.7-31.8] vs. 24.8 kg/m² [22.4-27.8], p < 0.001). Patients with PE had a significantly increased duration of the operation and more often underwent multivisceral resections. The lowest incidence of PE was found after distal or total pancreatectomy (2%). In median, PE occurred on the fifth postoperative day (interquartile range: 3-9). Increased BMI, duration of operation, and postoperative deep venous thrombosis were found to be multivariate risk factors for the development of PE. Importantly, postoperative complications (53.8% vs. 15.1%, p < 0.001) and the 30-day mortality rate were significantly increased in the PE group (19.2% vs. 3.3%, p < 0.001).

CONCLUSIONS

Patients with increased BMI, a history of deep venous thrombosis, and multivisceral resections are a high-risk group for PE after pancreatic surgery. While the absolute incidence and related mortality of PE after pancreatic surgery is low, it is associated with severe sequelae.

Clinicoradiological features of resected serous cystic neoplasms according to morphological subtype and preoperative tentative diagnosis: can radiological characteristics distinguish serous cystic neoplasms from other lesions?

Purpose

Serous cystic neoplasm (SCN) of the pancreas is considered benign in most cases. However, some SCN patients undergo surgical resection because lesions could not be differentiated preoperatively. This study evaluated causes of resection for SCN, investigated clinical and radiological features of surgically resected SCNs, and compared characteristics of SCNs diagnosed accurately and those misdiagnosed.

Methods

One hundred patients, who underwent surgery for pancreatic cystic tumors with pathological confirmation of SCN between 2000 and 2014 were retrospectively analyzed.

Results

The mean patient age was 52.9 years, 67 (67%) were female, and most lesions (72%) were located in the pancreatic body or tail. Fifty-one (51%) pathologically confirmed SCNs were preoperatively diagnosed as non-SCNs. Patients underwent surgery due to uncertain diagnosis (58%) or symptomatology (18%). According to radiological examination, most lesions were macrocystic (85%), exhibited septation (58%), or were enhancing lesions (48%). Compared with preoperatively diagnosed non-SCNs, accurately diagnosed SCNs exhibited septation (75.5% vs. 41.2%, P = 0.001) and central scar (36.7% vs. 11.8%, P = 0.003) more frequently in radiological examinations. In terms of macrocystic tumors (n = 85), most parameters did not differentiate preoperative diagnoses, although lesions accurately diagnosed as SCN exhibited septation more frequently than those preoperatively misdiagnosed as mucinous cystic neoplasm or intraductal papillary mucinous neoplasm (70.7% vs. 38.9% vs. 33.3%, respectively, P = 0.009).

Conclusion

It is difficult to accurately distinguish macrocystic SCNs from other cystic tumors using conventional radiological methods. For more accurate diagnosis, new biomarkers and/or other diagnostic modalities are needed and warrant further investigation.

Surveillance and management for serous cystic neoplasms of the pancreas based on total hazards-a multi-center retrospective study from China

Background

Serous cystic neoplasms (SCN) rarely have malignant potential, so accurate diagnosis of SCN is crucial for proper clinical management, especially to avoid unnecessary surgeries. However, the misdiagnosis of other pancreatic cystic neoplasm instead of SCN may highly increase the risk of malignancy in patients who receive no surgery.

Methods

Data from a total of 678 patients with pathologically confirmed to have SCN at sixteen institutions in China from January 1^st, 2006 to December 31^st, 2016 were retrieved to evaluate the malignancy risk of SCN.

Results

Among the 678 patients confirmed to have SCN with postoperative pathologic analysis, 649 patients (95.7%) had only one lesion and the average maximum diameter was 3.8±2.47 cm. Four patients were pathologically verified as having serous cystadenocarcinoma, so the SCN actual malignancy rate was 0.6%, while the mortality due to pancreatic surgery in these high-volume centers was nearly 0.2-2%. However, among the 99 SCN patients based on preoperative radiology, three were confirmed to have intraductal papillary mucinous neoplasms (IPMN), nine as mucinous cystic neoplasms (MCN), and four as solid pseudopapillary tumors (SPT) after postoperative pathological analysis. Thus, the total theoretical malignancy rate resulting from preoperative misdiagnosis was elevated to approximately 2.9%, higher than the risk of perioperative mortality.

Conclusions

When SCN can't be accurately distinguished from cystic tumors of pancreas, the malignant risk of cystic tumors may be higher than perioperative risk. However, if it can be diagnosed as SCN accurately, surgery can be avoided as well.

The Value of Contrast-Enhanced Ultrasound Classification in Diagnosis of Pancreatic Cystic Lesions

Objective

To compare the consistency of contrast-enhanced ultrasound (CEUS) classification results with magnetic resonance imaging (MRI) and to investigate the diagnostic value of CEUS classification in pancreatic cystic lesions.

Methods

84 cases of pancreatic cystic lesions were enrolled in this study. According to the CEUS classification methods of previous study in our center, all the lesions were classified into four types: type I, unilocular cysts; type II, microcystic lesions; type III, macrocystic lesions; and type IV, cystic lesions with enhanced solid components. The consistency of CEUS and MRI typing results was analysed. Among the 84 cases, 45 cases had pathological results. The CEUS results were compared with the pathological results, and the diagnostic value of CEUS classification in diagnosing pancreatic cystic lesions was explored.

Results

Among the 84 cases, CEUS diagnosed 8 cases of type I, 24 of type II, 8 of type III, and 45 of type IV. MRI diagnosed 10 cases of type I, 25 of type II, 7 of type III, and 43 of type IV. The classification typing results of CEUS were highly consistent with that of enhanced MRI (kappa value: 0.852). Among the 45 cases with pathological results, the diagnostic accuracy of each type was 91.1%, 95.6%, 93.3%, and 88.9%. The accuracy of CEUS and MRI in diagnosing pancreatic cystic lesions was 75.56% (34/45) and 80% (36/45), respectively. The diagnostic accuracy of CEUS had no significant difference from that of MRI (P=0.687).

Conclusion

The classification results by CEUS and MRI are in excellent agreement. The classification of pancreatic cystic lesions by CEUS is significantly helpful for clinical diagnosis.

Serous Neoplasms of the Pancreas: A Comprehensive Review

Serous neoplasms are uncommon, usually cystic tumors that account for less than 1% of all primary pancreatic lesions. They consist predominantly of a monomorphic epithelial cell population with a glycogen-rich, clear cytoplasm, reminiscent of clear cell renal cell carcinoma, with which serous neoplasms share an association with underlying VHL loss-of-function mutations. Serous neoplasms have no metastatic potential. Accurate recognition of this entity, including its various architectural subtypes, is critical to appropriate prognostication and treatment. Immunohistochemical detection of inhibin and calponin expression, along with the absence of both estrogen and progesterone receptors and nuclear β-catenin, can help to distinguish serous neoplasms from mimics. With the advent of minimally invasive and molecularly driven diagnostic techniques, the pathologist's role in the assessment and management of serous neoplasms has become increasingly complex and important. We provide an update on the histologic, immunohistochemical, and molecular features of pancreatic serous neoplasms for the practicing pathologist.

Giant symptomatic serous cystadenoma mimicking carcinoma: A case report and literature review

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The diagnosis of serous cystadenoma is challenging.

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Surgery may be indicated for select serous cystadenoma.

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Serous cystadenocarcinoma is a rare entity and histologically indistinguishable from its benign counterpart.

Introduction

Advanced imaging has led to an increase in the incidental diagnosis of pancreatic cysts. Serous cystadenomas (SCAs) account for nearly 30% of cases. These are typically considered benign lesions but up to 16% of cases are resected for aggressive behavior and symptoms.

Presentation of case

A 64 year old female presented with a large incidental cyst in the pancreatic body. Pre-operative imaging conferred a diagnosis of SCA. After 2 years the cyst grew resulting in abdominal pain. Enlargement was associated with splenic vein occlusion and varices of the short gastric vessels. This change in behavior was concerning for malignant transformation. The cyst was resected by distal pancreatectomy and splenectomy. The patient recovered with minimal morbidity. Final pathology revealed a 15.5 × 10.3 × 8.5 cm SCA with negative margins.

Discussion

In this case a patient presents with aggressive radiographic features and new symptoms suggesting malignant transformation of a previously diagnosed SCA on imaging. Although malignant variants can be diagnosed by findings of metastatic deposits at the time of surgery or as recurrence years later, histologic findings cannot discriminate benign from malignant potential. Preoperative imaging is challenging with erroneous characterization in nearly 60% of cases.

Conclusion

Based on the low risk of malignancy, selective surgical resection for SCA appears warranted. Accepted indications for surgery include development of symptoms or concern for correct diagnosis in a medically fit individual. Routine resection for cysts >4 cm has been suggested however, prospective studies are needed to determine benefit over risk rationale.

Growth rate of serous pancreatic neoplasms in vivo: a retrospective, observational study

BACKGROUND

Determining the growth rate of pancreatic cystic lesions on follow-up imaging is important in managing patients with these lesions. However, the growth rates of serous pancreatic neoplasms (SPNs) have been reported to vary among studies.

PURPOSE

To determine the in vivo growth rate of SPNs.

MATERIAL AND METHODS

This retrospective, single-institutional study included patients diagnosed with SPNs during 2006-2015. The diagnosis of SPNs was based on the results of surgery, endoscopic ultrasonography (EUS)-guided fine needle aspiration (FNA) or core needle biopsy (CNB), or typical radiologic features of SPN. A linear mixed-effects model was utilized to determine whether the diagnostic intervention was associated with tumor growth rate in all patients. The in vivo growth rate of SPNs was estimated from patients without or before diagnostic intervention. SPN growth rates were compared before and after diagnostic intervention.

RESULTS

SPN growth rates in the overall patient cohort (n = 304) differed significantly between patients who did and did not undergo diagnostic interventions. The in vivo SPN growth rate in 204 patients without or before diagnostic intervention was 1.9 mm/year (95% confidence interval [CI] = 1.6-2.2). In the 130 patients who underwent diagnostic intervention, the SPN growth rate was significantly greater before than after diagnostic intervention (1.8 vs. 0.2 mm/year).

CONCLUSIONS

In the absence of diagnostic intervention, the in vivo growth rate of SPNs was 1.9 mm/year (95% CI = 1.6-2.2). EUS-guided FNA or CNB may affect the growth rate of SPNs.

The "extracapsular cystic" sign in pancreatic serous cystic neoplasms: A clinicopathologic study of 177 patients with cystic pancreatic lesions

OBJECTIVE

To assess a new imaging feature that we have named the extracapsular cystic sign which can make a constructive contribution towards differentiating serous cystic neoplasms (SCNs) from other pancreatic cystic lesions.

MATERIAL AND METHODS

We retrospectively reviewed 177 CTs/MRIs of patients who underwent pancreatic resection of cystic lesions at two institutions from January 2011/2013, to September 2017. For each patient, demographic information, clinical presentation, especially imaging features were carefully investigated by two experienced abdominal radiologists, retrospectively. All statistical analyses were performed using SPSS V.23.0.

RESULTS

Twenty-one lesions had extracapsular cystic signs which were newly discovered, 17 (28.3%) of 60 SCNs and 4 (3.4%) (mucinous cystic neoplasm = 1, walled-off necrosis = 2, retention cyst = 1) of 117 Non-SCNs were included, from which indicating that the extracapsular cystic sign was more often detected on SCNs. As for 21 lesions, 86% (n = 18) were females, and mean age at diagnosis was 51.2 years. 71% (n = 15) located in the pancreatic body and tail. Average size was 27.2 mm (23.7-53.4), mean (SD) ratio of biggest daughter cyst to mother cyst was 0.51[0.14] (p = 0.99), average (SD) angle between two of them was 105.5° [14.9] (p = 0.84). The average time interval between last imaging examination and surgery was 8.4 days.

CONCLUSIONS

The new sign named the extracapsular cystic sign in SCNs may help differentiate SCNs from other pancreatic cystic lesions. Furthermore, this study supports an original diagnosis for SCNs when the sign of extracapsular cyst appears.

Prevalence, Diagnosis and Management of Pancreatic Cystic Neoplasms: Current Status and Future Directions

Cystic neoplasms of the pancreas are found with increasing prevalence, especially in elderly asymptomatic individuals. Although the overall risk of malignancy is very low, the presence of these pancreatic cysts is associated with a large degree of anxiety and further medical investigation due to concerns about malignancy. This review discusses the different cystic neoplasms of the pancreas and reports diagnostic strategies based on clinical features and imaging data. Surgical and nonsurgical management of the most common cystic neoplasms, based on the recently revised Sendai guidelines, is also discussed, with special reference to intraductal papillary mucinous neoplasm (IPMN; particularly the branch duct variant), which is the lesion most frequently identified incidentally. IPMN pathology, its risk for development into pancreatic ductal adenocarcinoma, the pros and cons of current guidelines for management, and the potential role of endoscopic ultrasound in determining cancer risk are discussed. Finally, surgical treatment, strategies for surveillance of pancreatic cysts, and possible future directions are discussed.

Serous cystic neoplasm of the pancreas: a multinational study of 2622 patients under the auspices of the International Association of Pancreatology and European Pancreatic Club (European Study Group on Cystic Tumors of the Pancreas)

OBJECTIVES

Serous cystic neoplasm (SCN) is a cystic neoplasm of the pancreas whose natural history is poorly known. The purpose of the study was to attempt to describe the natural history of SCN, including the specific mortality.

DESIGN

Retrospective multinational study including SCN diagnosed between 1990 and 2014.

RESULTS

2622 patients were included. Seventy-four per cent were women, and median age at diagnosis was 58 years (16-99). Patients presented with non-specific abdominal pain (27%), pancreaticobiliary symptoms (9%), diabetes mellitus (5%), other symptoms (4%) and/or were asymptomatic (61%). Fifty-two per cent of patients were operated on during the first year after diagnosis (median size: 40 mm (2-200)), 9% had resection beyond 1 year of follow-up (3 years (1-20), size at diagnosis: 25 mm (4-140)) and 39% had no surgery (3.6 years (1-23), 25.5 mm (1-200)). Surgical indications were (not exclusive) uncertain diagnosis (60%), symptoms (23%), size increase (12%), large size (6%) and adjacent organ compression (5%). In patients followed beyond 1 year (n=1271), size increased in 37% (growth rate: 4 mm/year), was stable in 57% and decreased in 6%. Three serous cystadenocarcinomas were recorded. Postoperative mortality was 0.6% (n=10), and SCN's related mortality was 0.1% (n=1).

CONCLUSIONS

After a 3-year follow-up, clinical relevant symptoms occurred in a very small proportion of patients and size slowly increased in less than half. Surgical treatment should be proposed only for diagnosis remaining uncertain after complete workup, significant and related symptoms or exceptionally when exists concern with malignancy. This study supports an initial conservative management in the majority of patients with SCN.

TRIAL REGISTRATION NUMBER

IRB 00006477.

Laparoscopic fenestration of pancreatic serous cystadenoma: Minimally invasive approach for symptomatic benign disease

Serous cystadenoma (SC) is a benign pancreatic cystic tumor. Surgical resection is recommended for symptomatic forms, but laparoscopic fenestration of large symptomatic macrocystic SC was not yet described in the literature. In this study, 3 female patients underwent laparoscopic fenestration for macrocystic SC (12-14 cm). Diagnosis was established via magnetic resonance imaging and endoscopic ultrasound, with intra-cystic dosage of tumors markers (ACE and CA19-9) in 2 patients. All patients were symptomatic and operated on 15-60 mo after diagnosis. Radiological evaluation showed constant cyst growth. Patients were informed about this new surgical modality that can avoid pancreatic resection. The mean operative time was 103 min (70-150 min) with one conversion. The post-operative course was marked by a grade A pancreatic fistula in one patient and was uneventful in the other two. The hospital stay was 3, 10, and 18 d, respectively. The diagnosis of macrocystic SC was histologically-confirmed in all cases. At the last follow-up (13-26 mo), all patients were symptom-free, and radiological evaluation showed complete disappearance of the cyst. Laparoscopic fenestration, as opposed to resection, should be considered for large symptomatic macrocystic SC, thereby avoiding pancreatic resection morbidity and mortality.

Spleen preservation in a caudal pancreatic serous cystadenoma - case report

Cystic lesions of the pancreas are relatively rare entities but have been increasingly diagnosed in recent years due to advanced imaging techniques. This category encompasses pancreatic pseudocyst as well as a wide range of pancreatic tumors with benign behavior, borderline or primary malignant. Serous cystadenoma of the pancreas represents the most common benign pancreatic tumor, with a very low but well recognized malignant potential. The clinical presentation varies according to its size; small tumors may be asymptomatic and discovered incidentally, while large tumors are more likely symptomatic. We report the case of a female patient presenting with non-specific left abdominal pain, who was diagnosed through a CT scan with a caudal pancreatic tumor. The patient underwent spleen-preserving distal pancreatectomy. The result of the histopathological examination revealed a serous cystadenoma.

Management of serous cystic neoplasms of the pancreas

Pancreatic serous cystadenomas are uncommon benign tumours that are often found incidentally on routine imaging examinations. Radiological imaging techniques alone have proven to be suboptimal to fully characterize cystic pancreatic lesions. Endoscopic ultrasound, with the addition of fine-needle aspiration in difficult cases, has showed greater diagnostic accuracy than conventional imaging techniques. The best management strategy of these neoplasms is still debated. Surgery should be limited only to symptomatic and highly selected cases and most of the patients should only be strictly monitored. In the current paper, we provide an updated overview on pancreatic serous cystadenomas, focusing our attention on epidemiology, clinical characteristics and diagnostic evaluation; finally, we also discuss different management strategies and areas for future research.

Rate of growth of pancreatic serous cystadenoma as an indication for resection

BACKGROUND

The purpose of this study was to examine the natural history and growth rate of pancreatic serous cystadenomas (SCAs) to determine which factors lead to resection for these benign neoplasms.

METHODS

We reviewed retrospectively a prospectively maintained database, identifying patients diagnosed with SCAs of the pancreas. The diagnosis was made via a combination of classic imaging features with or without cyst aspiration results consistent with SCA. To determine growth rates, gamma regression models were used and the average was modeled using the log function.

RESULTS

A prospectively maintained database of 1,241 pancreatic cystic neoplasms was queried from 1998 to 2010. A total of 219 patients (18%) were diagnosed with SCA, 194 in the surveillance group and 25 in the resection group. Twenty patients underwent resection after initial imaging principally for presence of symptoms and indeterminate diagnosis, and 5 underwent resection after surveillance for development of symptoms and/or rapid rate of growth. Rate of growth increased at a steady state over time, with an estimated doubling time of 12 years (95% confidence interval, 7.8-21.5).

CONCLUSION

This study shows that growth patterns are similar for SCAs of the pancreas regardless of initial size. When doubling time is faster than 12 years, resection should be considered.

Diagnosis and treatment of pancreatic pseudocysts and cystic tumors based on own material and quoted literature

Pseudocysts constitute the most basic cystic lesions of the pancreas. Symptomatic cysts may be treated by means of both minimally invasive methods and surgery. Currently, it is believed that approximately 5% of cystic lesions in the pancreas may in fact, be neoplastic cystic tumors. Their presence is manifested by generally irregular multilocular structures, solid nodules inside the cyst or in the pancreatic duct, frequently vascularized, as well as fragmentary thickening of the cystic wall or septation.

Spleen-preserving laparoscopic distal pancreatectomy: Two cases and review of the technique

In this study, we aimed to assess the technique and results of spleen-preserving laparoscopic distal pancreatectomy (SPLDP) on the basis of two cases. The first case was a woman with a large cystic papillary lesion of the distal pancreas. The other patient was a woman with a pancreatic mass on the tail of the pancreas. Both patients were operated on using SPLDP. Five trocars were used in the first case and four trocars were used in the second case. Thirty degree telescope visualization and LigaSure dissection were used during the operation. The splenic vessels were dissected, but the short gastric vessels were preserved. The pancreas was transected by one Endo GIA stapler and the cut edge of the pancreas was reinforced with sutures to prevent a pancreatic fistula. We performed the same technique in both cases. However, in the first case, we aspirated the content of the cystic mass of the pancreas before removing it to avoid making a large incision. The duration of the operation was 190 and 135 minutes, respectively. There were no postoperative complications. SPLDP is a safe, effective modality for managing lesions of the distal pancreas. If the splenic vessels are transected, the short gastric vessels must be protected to ensure the viability of the spleen.