A case of acinar cell carcinoma originating from the accessory papilla of the duodenum.

CASE PRESENTATION: A 61-year-old female was referred to our hospital with a neoplastic lesion in the duodenum. Computed tomography with contrast enhancement revealed a 10-mm tumor in the duodenum. Upper gastrointestinal endoscopy revealed a submucosal tumor-like lesion in the descending part of the duodenum. Endoscopic ultrasound revealed a well-defined hypoechoic tumor. Biopsy and immunohistochemical findings including negative Synaptophysin and Chromogranin A staining and positive Trypsin and BCL10 staining suggested a carcinoma with acinar cell differentiation. Pancreatoduodenectomy was performed, and the resected specimen had a 15-mm solid nodule in the submucosal layer of the duodenum. Pancreatogram of the resected specimen revealed a tumor localized in the accessory papilla region. In histopathological examination, the tumor was found in the submucosa of the duodenum with pancreatic tissue present nearby, and these were separated from the pancreatic parenchyma by the duodenal muscle layer. These findings led to a diagnosis of acinar cell carcinoma originating from the accessory papilla of the duodenum. CONCLUSION: Acinar cell carcinoma originating from the accessory papilla of the duodenum is exceptionally rare, with no reported cases to date. The origin was considered to be pancreatic tissue located in the accessory papilla region.

Factors Affecting Nonfunctioning Small Pancreatic Neuroendocrine Neoplasms and Proposed New Treatment Strategies.

BACKGROUND & AIMS: Despite previously reported treatment strategies for nonfunctioning small (≤20 mm) pancreatic neuroendocrine neoplasms (pNENs), uncertainties persist. We aimed to evaluate the surgically resected cases of nonfunctioning small pNENs (NF-spNENs) in a large Japanese cohort to elucidate an optimal treatment strategy for NF-spNENs. METHODS: In this Japanese multicenter study, data were retrospectively collected from patients who underwent pancreatectomy between January 1996 and December 2019, were pathologically diagnosed with pNEN, and were treated according to the World Health Organization 2019 classification. Overall, 1490 patients met the eligibility criteria, and 1014 were included in the analysis cohort. RESULTS: In the analysis cohort, 606 patients (59.8%) had NF-spNENs, with 82% classified as grade 1 (NET-G1) and 18% as grade 2 (NET-G2) or higher. The incidence of lymph node metastasis (N1) by grade was significantly higher in NET-G2 (G1: 3.1% vs G2: 15.0%). Independent factors contributing to N1 were NET-G2 or higher and tumor diameter ≥15 mm. The predictive ability of tumor size for N1 was high. Independent factors contributing to recurrence included multiple lesions, NET-G2 or higher, tumor diameter ≥15 mm, and N1. However, the independent factor contributing to survival was tumor grade (NET-G2 or higher). The appropriate timing for surgical resection of NET-G1 and NET-G2 or higher was when tumors were >20 and >10 mm, respectively. For neoplasms with unknown preoperative grades, tumor size >15 mm was considered appropriate. CONCLUSIONS: NF-spNENs are heterogeneous with varying levels of malignancy. Therefore, treatment strategies based on tumor size alone can be unreliable; personalized treatment strategies that consider tumor grading are preferable.

Novel Repair Technique for Oral and Anal Side Stoma Prolapse of a Loop Colostomy With the Stapled Modified Altemeier Method Using Indocyanine Green Fluorescence Imaging.

BACKGROUND/AIM: Stoma prolapse is a common complication in the late phase after stoma creation. With advances in chemotherapy, a double-orifice colostomy or ileostomy and chemotherapy are used to treat primary unresectable colorectal cancer. Preoperative therapy with a double-orifice colostomy or ileostomy is performed to aid primary colorectal cancer miniaturization. Therefore, the number of stoma prolapses will likely increase in the future. Previous reports on the repair of stoma prolapse focused on unilateral stoma prolapse of loop colostomy, and there are no reports about the bilateral stoma prolapse of loop colostomy or ileostomy. CASE REPORT: We report a novel repair technique for oral and anal side (bilateral) stoma prolapse of a loop colostomy with the stapled modified Altemeier method using indocyanine green (ICG) fluorescence imaging considering the distribution of marginal artery in preventing marginal artery injury which has considerable clinical significance. CONCLUSION: Our novel technique for the oral and anal side prolapse of a loop colostomy is considered effective and safe.

A case of simultaneous breast cancer and ovarian cancer based on a hereditary breast and ovarian cancer syndrome.

We experienced a relatively rare case of synchronous breast and ovarian cancer in a patient with hereditary breast and ovarian cancer syndrome (HBOC). Here, we report the usefulness of laparoscopic examination to determine the subsequent treatment strategy in cases of suspected concurrent multiple carcinomas. Our patient was diagnosed with breast cancer following detection of a right breast mass. She was diagnosed with HBOC as she was found to be harboring a germline pathogenic variant of breast cancer susceptibility gene 1 (BRCA1). Preoperative images suggested the presence of neoplastic masses in the abdominal cavity, and the possibility of metastatic peritoneal dissemination of breast cancer or concurrent overlapping of gynecological malignancies was considered. We decided to employ laparoscopic examination, and if simultaneous overlapping of cancers was suspected, we planned to further evaluate whether primary debulking surgery (PDS) for gynecological cancer was possible or not. Laparoscopy revealed the presence of ovarian cancer with neoplastic lesions on the bilateral ovaries and disseminations in the pelvic and abdominal cavities. The total predictive index was 0; therefore, PDS was considered feasible. We performed a total mastectomy, followed by laparotomy, and optimal surgery was achieved. The final diagnosis was simultaneous stage IIB invasive ductal breast carcinoma and stage IIIC high-grade serous ovarian carcinoma. In this case of suspected concurrent multiple carcinomas, laparoscopy was beneficial for decision-making regarding subsequent surgical treatment. We believe that the use of laparoscopy will enable simultaneous surgery for breast cancer and ovarian cancer to become one of the treatment strategies in the future.

Three cases of open surgical procedures on ileal conduits for the repair of benign ureteroenteric anastomotic strictures after total pelvic exenteration of rectal tumors.

Ureteroenteric anastomotic strictures (UEAS) are typical complications after creating an ileal conduit for total pelvic exenteration (TPE) of rectal tumors. We report the ileal conduit for reconstruction in three patients, in the age-range of 47-73 years. Case 1 was when a left-sided UEAS had sufficient length of ureter for anastomosis, Case 2 was a right-sided UEAS with sufficient length of ureter for anastomosis, and Case 3 was a left-sided UEAS with insufficient length of ureter for anastomosis. There were no complications after operation and no recurrence of UEAS. It is important to learn the open surgical procedures for repair of a benign UEAS after TPE of rectal cancers. This has fewer complications and is safe in the long term.

How many times can patients tolerate reoperation for the local recurrence of colorectal cancer in terms of complications?

The frequency of resection for the recurrence of colorectal cancer has not been investigated in previous studies. Likewise, the related postoperative complications and the limit for indicating surgical resection has not been reported. Herein, we reported the complications of a highly frequent surgical approach for rectal cancer recurrence, i.e., exceeding three reoperations, based on our clinical experience. We included 15 cases exceeding two operations for the local recurrence of colorectal cancer from 2014 to 2019. We examined the postoperative complications classified as Clavien?Dindo IIIb. The positive rates of the complications were 0 (0.0%), 0 (0.0%), 2 (13.3%), 3 (37.5%), and 0 (0.0%) for the primary, 1st recurrent, 2nd recurrent, 3rd recurrent, and 4th recurrent operation group (p=0.027), respectively. It is important to exercise caution in handling cases exceeding two reoperations (exceeding three reoperations including the primary operation). J. Med. Invest. 70 : 369-376, August, 2023.

Novel Ureteral Stent Catheterization Technique for Treating Hyperchloremic Metabolic Acidosis After Total Pelvic Exenteration.

BACKGROUND/AIM: Hyperchloremic metabolic acidosis after total pelvic exenteration (TPE) is relatively rare. Urinary diversion of the ileal conduit during TPE can result in increased urine reabsorption leading to hyperchloremic metabolic acidosis. We developed a new technique for the retrograde catheterization of a ureteral stent into an ileal conduit to treat hyperchloremic metabolic acidosis. CASE REPORT: A 70-year-old man underwent TPE for locally recurrent rectal cancer. Multiple episodes of complications, such as hyperchloremia and metabolic acidosis, occurred. Effective drainage of urine from the ileal conduit is crucial. With collaboration between an endoscopist and a radiologist, we developed a novel method for retrograde catheterization of the ureteral stent into an ileal conduit for hyperchloremic metabolic acidosis after TPE. The patient's condition quickly improved after the procedure. CONCLUSION: Our novel technique of retrograde catheterization of a ureteral stent into an ileal conduit for hyperchloremic metabolic acidosis could be adopted worldwide, as it is effective and safe.

Features of T1 pancreatic cancer and validation of the eighth edition AJCC staging system definition using a Korean-Japanese joint cohort and the SEER database.

BACKGROUND/PURPOSE: Little is known about the features of T1 pancreatic ductal adenocarcinoma (PDAC) and its definition in the eighth edition of the American Joint Committee on Cancer (AJCC) staging system needs validation. The aims were to analyze the clinicopathologic features of T1 PDAC and investigate the validity of its definition. METHOD: Data from 1506 patients with confirmed T1 PDAC between 2000 and 2019 were collected and analyzed. The results were validated using 3092 T1 PDAC patients from the Surveillance, Epidemiology, and End Results (SEER) database. RESULTS: The median survival duration of patients was 50 months, and the 5-year survival rate was 45.1%. R0 resection was unachievable in 10.0% of patients, the nodal metastasis rate was 40.0%, and recurrence occurred in 55.2%. The current T1 subcategorization was not feasible for PDAC, tumors with extrapancreatic extension (72.8%) had worse outcomes than those without extrapancreatic extension (median survival 107 vs. 39 months, p < .001). Extrapancreatic extension was an independent prognostic factor whereas the current T1 subcategorization was not. The results of this study were reproducible with data from the SEER database. CONCLUSION: Despite its small size, T1 PDAC displayed aggressive behavior warranting active local and systemic treatment. The subcategorization by the eighth edition of the AJCC staging system was not adequate for PDAC, and better subcategorization methods need to be explored. In addition, the role of extrapancreatic extension in the staging system should be reconsidered.

Tranexamic acid and blood loss in pancreaticoduodenectomy: TAC-PD randomized clinical trial.

BACKGROUND: Tranexamic acid (TXA) may reduce intraoperative blood loss, but it has not been investigated in pancreaticoduodenectomy (PD). METHODS: A pragmatic, multicentre, randomized, blinded, placebo-controlled trial was conducted. Adult patients undergoing planned PD for biliary, duodenal, or pancreatic diseases were randomly assigned to TXA or placebo groups. Patients in the TXA group were administered 1 g TXA before incision, followed by a maintenance infusion of 125 mg/h TXA. Patients in the placebo group were administered the same volume of saline as those in the placebo group. The primary outcome was blood loss during PD. The secondary outcomes included perioperative blood transfusions, operating time, morbidity, and mortality. RESULTS: Between September 2019 and May 2021, 218 patients were randomly assigned and underwent surgery (108 in the TXA group and 110 in the placebo group). Mean intraoperative blood loss was 659 ml in the TXA group and 701 ml in the placebo group (mean difference -42 ml, 95 per cent c.i. -191 to 106). Of the 218 patients, 202 received the intervention and underwent PD, and the mean blood loss during PD was 667 ml in the TXA group and 744 ml in the placebo group (mean difference -77 ml, 95 per cent c.i. -226 to 72). The secondary outcomes were comparable between the two groups. CONCLUSION: Perioperative TXA use did not reduce blood loss during PD. REGISTRATION NUMBER: jRCTs041190062 (https://jrct.niph.go.jp).

Removing part of the pancreas is an operation with a risk of major blood loss. Tranexamic acid is a drug thought to reduce blood loss. This study asked the question, 'Does tranexamic acid reduce blood loss during surgery on the pancreas?' Half of patients received tranexamic acid during surgery. The other half received only standard care. This study showed that tranexamic acid did not decrease the blood loss during the surgery and may have little effect in patients having a pancreaticoduodenectomy.

Total Pelvic Exenteration Combined With Sacral Resection for Rectal Cancer.

BACKGROUND: This retrospective study aimed to demonstrate surgical operative approach of total pelvic exenteration combined with sacral resection with rectal cancer and elucidate the relationships between the level of sacral resection and short-term outcomes. METHODS: Twenty cases were selected. Data regarding sex, age, body mass index, neoadjuvant therapy, location of sacral resection ("Upper" or "Lower" relative to the level between the 3rd and 4th sacral segment), operative time, bleeding, and curability (R0/R1) were collected and compared to determine their association with complications exhibiting a Clavien-Dindo grade III. RESULTS: The complication rate was significantly higher for recurrent cancers (n = 10, 76.9%) than for primary cancers (n = 1, 14.3%) (P = .007), and for "Upper" resection (n = 8, 72.7%) than for "Lower" resection (n = 3, 33.3%) (P = .078). Significant differences were observed when complication rates for "Lower" and primary cancer resection (n = 3, .0%) were compared between "Upper" and recurrent cancers (n = 8, 100.0%) (P = .007). CONCLUSION: In patients with recurrent rectal cancer, "Upper" sacral resection during total pelvic exenteration is associated with a high complication rate, highlighting the need for careful monitoring.

Impact of pancreatic fat infiltration on postoperative pancreatic fistula occurrence in patients undergoing invagination pancreaticojejunostomy.

BACKGROUND: No studies to date have determined the impact of pancreatic fat infiltration on postoperative pancreatic fistula (POPF) occurrence in patients undergoing invagination pancreaticojejunostomy (IV-PJ). METHODS: The medical records of patients with a soft pancreas who underwent pancreatoduodenectomy followed by IV-PJ were reviewed . The pancreatic fat ratio on computed tomography (CT) images (I-PFR) was determined using preoperative CT and verified by histologic examination. The relationship between the I-PFR and POPF occurrence was determined. Patients were classified into 2 groups based on I-PFR value (fatty and non-fatty pancreas). Postoperative outcomes were compared between the two groups, and specifically among patients who developed POPF. RESULTS: Of 221 patients, POPF occurred in 67 (30.3%). I-PFR was positively correlated with histologic-calculated fat ratio (ρ = 0.517, p < 0.001). This index was shown to be an independent predictor of POPF. Based on an I-PFR cut-off value of 3.2%, 92 patients were classified in the fatty pancreas group. Subgroup analysis of the patients who developed POPF showed that incidence of abscess formation and hemorrhage tended to be higher in patients with fatty pancreas than in those with non-fatty pancreas. CONCLUSIONS: Pancreatic fat infiltration is highly associated with POPF and possibly causes subsequent serious complications in patients undergoing IV-PJ.

Prognostic Significance of Intraoperative Peritoneal Lavage Cytology in Patients with Pancreatic Ductal Adenocarcinoma: A Single-Center Experience and Systematic Review of the Literature.

BACKGROUND: The prognostic significance of peritoneal lavage cytology (PLC) in patients with pancreatic ductal adenocarcinoma (PDAC) remains controversial. The purpose of this study was to evaluate the prognostic impact of PLC status in PDAC patients. METHODS: Patients intending to undergo resection for PDAC between 2007 and 2020 were included. Survival was compared among patients who underwent resection with negative or positive PLC status and those who did not undergo resection. Univariable and multivariable analyses were conducted to evaluate the prognostic impact of positive PLC status. A systematic literature review was performed to evaluate the correlation between prognosis and the positive PLC rate. RESULTS: A total of 480 patients formed the study cohort and were divided as follows: 438 in the negative PLC group, 18 in the positive PLC group, and 24 in the no resection group. Although the median survival time significantly differed between the negative and positive PLC groups (35.7 vs. 13.6 months, P < 0.001), it did not significantly differ between the positive PLC and no resection groups (13.6 vs. 12.2 months, P = 0.605). Multivariable analyses demonstrated that positive PLC status (hazard ratio = 3.54, 95% confidence interval = 1.97-6.38, P < 0.001) was the strongest poor prognostic factor. Based on statistical analyses for the systematic review, the prognostic impact of positive PLC status weakened significantly as the institutional positive PLC rate increased (P = 0.044). CONCLUSIONS: Resection did not improve the prognosis of patients with positive PLC status in our cohort. The institutional positive PLC rate may be a good reference for surgical indication in these patients.

A new option for laparoscopic spleen-preserving distal pancreatectomy: three cases with splenic artery preservation and resection of the splenic vein.

There are two techniques for a spleen-preserving distal pancreatectomy (SPDP): SPDP with splenic vessel preservation, and SPDP with splenic vessel resection. In some cases, although the splenic artery (SpA) can be preserved, the splenic vein (SpV) must be resected. We report the short- and long-term outcomes of three patients who underwent a new technique of laparoscopic SPDP with SpA preservation and SpV resection (SPDP-VRes). A grade B pancreatic fistula, which occurred in two patients, was successfully treated with drainage tube management. In all cases, the omental branches of the left gastroepiploic vein functioned as a drainage vein, and there was no splenomegaly, thrombocytopenia, or varix formation during the follow-up period (19 months to 5 years). Patients undergoing laparoscopic SPDP-VRes had no severe complications during the follow-up period; preserving the left omental branch is a key to this procedure. Laparoscopic SPDP-VRes might be a useful treatment option for patients undergoing SPDP.

Portal vein leiomyosarcoma invading the pancreatic head.

We encountered a rare case of a pancreatic head tumor protruding into the portal vein, later diagnosed histopathologically as primary leiomyosarcoma of the portal vein. A 59-year-old woman visited our hospital because of an elevated amylase level during a medical checkup. Computed tomography showed a moderately contrasted, well-defined mass of 35-mm diameter in the pancreatic head with protrusion into the portal vein. Endoscopic ultrasonography revealed a well-defined and hypoechoic mass. Fluorodeoxyglucose-positron emission tomography showed a high accumulation of fluorodeoxyglucose in the pancreas head. We performed a subtotal stomach-preserving pancreaticoduodenectomy with portal vein resection. Gross findings of the fixed specimen showed a white solid, multinodular mass in the pancreatic parenchyma with protrusion into the portal vein. Histopathological examination showed proliferation of spindle-shaped eosinophilic cells with intricate bundle-like growth, indicating leiomyosarcoma. Examining the tumor location and invasion suggested portal vein as the origin. Although portal vein primary leiomyosarcoma is rare, leiomyosarcoma should be considered as a differential diagnosis in pancreatic head tumors with protrusion into the portal vein. Precise macroscopic and histopathological examinations can help determine the definitive diagnosis and origin of leiomyosarcoma.

Repair of antegrade anastomosis between ileal segment and amputated ureter for recurrent rectal cancer.

We describe a case of repair of the antegrade anastomosis between the "ileal segment" and amputated ureter for recurrent rectal cancer, in which some postoperative complications occurred but eventually resolved. If the length of the ureter is inadequate for end-to-end anastomosis, an ileal segment can be used as a conduit. This surgical technique is not difficult because an ileal conduit is typically created during total pelvic exenteration of rectal cancers. Therefore, anastomosing the ureter to an "ileal segment" is easy and feasible. Hence, we consider that knowledge of this technique would be beneficial for surgical oncologists who perform colorectal surgeries.

Survival benefit of surgery for very elderly patients with pancreatic cancer: what extent of pancreatectomy is acceptable?

The purpose of this study is to clarify the survival benefit and acceptable extent of surgery for very elderly patients with pancreatic cancer. Patients (n=55) ≥80 years with resectable pancreatic cancer were studied. 29 underwent pancreatectomy, 16 underwent chemotherapy, and 10 received best supportive care. Uni and multivariate analysis were performed to explore predictive factors for overall survival (OS) with surgery and chemotherapy (n=45). Postoperative survival of PD (pancreatoduodenectomy) and DP (distal pancreatectomy) and of PD-PVR (PD with portal vein resection) and PD were compared. OS was equivalent with surgery and chemotherapy (median survival time [MST]; 685 vs. 626 days, respectively; p=0.057); 6 patients surivived ≥3 years after surgery. Pancreatectomy was not a prognostic factor. Survival was significantly worse with PD-PVR than with PD, but equivalent with PD and DP. Within 2 years after PD-PVR, 8 patients have died. Surgery was not a positive prognostic factor for very elderly patients with pancreatic cancer, but was the sole chance for survival ≥3 years. Indication for PD-PVR for very elderly patients should be determined more cautiously compared with that for non-elderly patients.

Continuous suture is a risk factor for benign hepaticojejunostomy stenosis after pancreatoduodenectomy in patients with a non-dilated bile duct.

BACKGROUND: It is unclear whether hepaticojejunostomy with a continuous suture is suitable for patients with a non-dilated bile duct. METHODS: Medical records of patients who underwent pancreatoduodenectomy between 2003 and 2013 were retrospectively reviewed, focusing on the incidence of benign anastomotic stenosis and its relationship with suture method (continuous vs interrupted) and common hepatic duct size. RESULTS: Among 336 patients, 172 had a non-dilated (<8 mm) duct, and the remaining 164 had a dilated duct. Benign stenosis occurred in 12.2% (21/172) in the former, but in only 0.6% (1/164) in the latter (p < 0.001; median follow-up period, 43.5 months). Thus, further analysis was conducted in the 172 patients with a non-dilated duct, among whom 116 received a continuous suture and 56 received an interrupted suture. The cumulative incidence of benign anastomotic stenosis was significantly higher in patients who received a continuous suture vs those who received an interrupted suture (15.6% vs 1.8%, respectively, at 3 years; p = 0.006). Multivariable analysis identified continuous suture, male gender, and cholangitis (within 3 months after surgery) as independent risk factors for benign stenosis. CONCLUSIONS: In this observational study, the use of a continuous suture was associated with benign anastomotic stricture in patients with a non-dilated hepatic duct.

Aggressive and frequent resection of recurrences in retroperitoneal sarcoma contributes to long-term survival.

PURPOSE: Retroperitoneal sarcoma (RPS) is a rare tumor with a poor prognosis and is often undetected until it is significantly enlarged. While surgical resection remains the primary treatment, there is little research on its benefits, especially that concerning the reoperation of recurrent disease. This study investigated the impact of surgical procedures, especially reoperation of recurrent RPS, on prognosis. METHODS: This retrospective study included 51 patients who underwent radical resection surgery (R0 status) for primary or recurrent RPS without distant metastasis. Patient outcomes and prognosis were defined in terms of the clinicopathologic factors and surgical techniques performed. RESULTS: In all cases, the 5-year disease-free survival (DFS) rate was 28.2%, 5-year overall survival rate was 89.9%, and 5-year no residual liposarcoma rate was 54.3% after operation and re-reoperation. There was a statistically significant difference between the 5-year DFS rate and 5-year no residual liposarcoma rate due to frequent re-reoperation (p = 0.011). On univariate analysis of primary and recurrent lesions, the histological type and the number of organs involved were identified as statistically significant prognostic factors. Patients with well-differentiated liposarcomas had a statistically better prognosis than those with other cancer types (primary RPS, p = 0.028; recurrence, p = 0.024). CONCLUSIONS: Aggressive and frequent resection of recurrent RPS with combined resection of adjacent organs contributes to long-term survival. The establishment of a surgical strategy for RPS will require a prospective study.

Gastroduodenal artery pseudoaneurysm hemorrhage 1 year after laparoscopic distal gastrectomy: a case report.

BACKGROUND: Postoperative bleeding originating from pseudoaneurysms after radical gastrectomy is not common, but it can be fatal. In particular, delayed bleeding that occurs after the seventh postoperative day is rare. CASE PRESENTATION: A 54-year-old man underwent laparoscopic distal gastrectomy, D2 lymph node dissection, and Roux en-Y reconstruction for duodenal neuroendocrine tumors. Drainage was performed for a postoperative pancreatic fistula and abdominal abscess. On the 28th postoperative day, he passed a large amount of bloody stool; therefore, emergency esophagogastroduodenoscopy (EGD) and angiography were performed. However, neither examination demonstrated any bleeding foci or pseudoaneurysm. He was conservatively observed and discharged on the 50th postoperative day. Approximately 1 year after the surgery, he passed a bloody stool and experienced hemorrhagic shock. An EGD revealed exposed blood vessels at the duodenal blind end. His condition was diagnosed as a pseudoaneurysm arising from gastroduodenal artery, which ruptured into the duodenum, based on abdominal contrast-enhanced computed tomography findings. Emergency angiography was performed, and the pseudoaneurysm and artery were successfully embolized. CONCLUSIONS: This case illustrates that there is a possibility of delayed bleeding even 1 year after gastrectomy. Such cases may be serious and require immediate and careful management.

Comparison of prognosis between observation and surgical resection groups with small sporadic non-functional pancreatic neuroendocrine neoplasms without distant metastasis.

BACKGROUND: The treatment of small (≤ 2 cm), sporadic localized non-functional pancreatic neuroendocrine neoplasms (PNENs) is often controversial. This study aimed to investigate the clinical outcomes with observation and surgical resection in small PNENs. METHODS: Seventy-five patients with small localized sporadic non-functional PNENs ≤ 2 cm, who underwent observation or surgical resection, were retrospectively reviewed. Changes in tumor size during follow-up in the observation group were also investigated. RESULTS: The median age of the cohort was 61 (range 35-81) years. The tumor grades were G1, G2, and unknown, in 61 (81.3%), 8 (10.7%), and 6 (8.0%) patients, respectively. The mean follow-up periods in the observation (n = 23) and surgical resection groups (n = 52) were 52.3 (range 6.8-133.3) months and 73.0 (range 9.1-179.9) months, respectively. The median overall survival was not reached. During follow-up, no patient died of PNENs, two died of other diseases, three had lymph node metastases, and one experienced recurrence after surgical resection. There was no significant difference in overall survival between the observation and surgical resection groups (hazard ratio: 0.031, P = 0.417). The mean change in tumor size in the observation group was + 0.30 mm (range - 1.6 to + 3.0 mm). No deaths, tumor progression, lymph node metastases, distant metastases, or recurrence were noted in patients with PNENs ≤ 1 cm (n = 36). CONCLUSIONS: The prognosis of small localized PNENs is good. Observation may be an alternative to surgery in high-risk patients and those with small G1 tumors, particularly those measuring ≤ 1 cm.