Malignant Insulinoma: A Rare Form of Neuroendocrine Tumor

Ethanol Ablation for Benign Insulinoma: Intraoperative and Endoscopic Approaches

INTRODUCTION

Ethanol ablation can be utilized to manage insulinoma. We aimed to analyze our outcomes of endoscopic ultrasound (EUS) and intraoperative ultrasound (IOUS) guided Ethanol ablation of insulinoma.

METHODS

A single institution retrospective review of adults undergoing Ethanol ablation of benign pancreatic insulinoma (2007-2022) was performed. Outcomes were categorized as resolution of hypoglycemia, improvement, or no change at last follow-up.

RESULTS

A total of 16 patients underwent Ethanol ablation of benign insulinoma (N = 8 EUS, N = 8 IOUS): median age was 68 y, 8 (50%) were females, and 2 (12.5%) were associated with multiple endocrine neoplasia type-1. Median insulinoma size was 12 (range 7, 25) mm. Ethanol ablation was preferred over resection to avoid pancreaticoduodenectomy when it was not possible to enucleate the tumor in 10 (62.5%) patients while the rest underwent ablation due to being poor surgical candidates or because of a history of previous pancreatic resection. The median follow-up (interquartile range) was 43 (19.5, 81.5) mo. Resolution of hypoglycemia occurred in 11 patients (5 EUS, 6 IOUS), while the rest (3 EUS, 2 IOUS) experienced improvement in the severity and frequency of hypoglycemia. A single patient underwent resection following a previous ablation for symptomatic hypoglycemia 5 y after EUS guided ablation.

CONCLUSIONS

Ethanol ablation provides an alternative therapeutic option for patients with insulinoma. Both EUS and IOUS guided approaches are associated with a favorable resolution rate although EUS guided ablation may require multiple procedures to optimize outcomes.

A review of functional pancreatic neuroendocrine tumors: Exploring the molecular pathogenesis, diagnosis and treatment

Pancreatic neuroendocrine tumors (PanNETs) are a rare subtype of pancreatic cancer and can be divided into functional (30-40%) and nonfunctional subtypes. The different subtypes of functional PanNETs (F-PanNETs) have a variety of classical presentations that raise suspicion for an underlying PanNET. It is estimated that 90% of PanNETs are sporadic, and the PI3K-Akt-mTOR and ATRX/DAXX signaling pathways have been recognized as key genetic pathways implicated in the pathogenesis. The other 10% of PanNETs may occur in the context of familial cancer syndromes such as MEN1. Chromogranin A is the most useful biomarker currently; however, several studies have shown limitations with its use, especially its prognostic value. Synaptophysin is a novel biomarker which has shown promising preliminary results however its use clinically has yet to be established. Blood tests assessing hormone levels, cross-sectional imaging, and endoscopic ultrasound remain at the core of establishing a diagnosis of F-PanNET. The treatment options for F-PanNETs include surgical methods such as enucleation, systemic therapies like chemotherapy and novel targeted therapies such as everolimus. The prognosis for F-PanNETs is more favorable than for nonfunctional PanNETs, however metastatic disease is associated with poor survival outcomes. Researchers should also focus their efforts on identifying novel pathways implicated in the pathogenesis of F-PanNETs in order to develop new targeted therapies that may reduce the need for surgical intervention and on the establishment of novel biomarkers that may reduce the need for invasive testing and allow for earlier detection of F-PanNETs.

Transformation of pancreatic nonfunctioning neuroendocrine tumor into metastatic insulinoma: A rare case report

Pancreatic neuroendocrine tumors can be classified as functional or nonfunctional based on hormone secretion. Management of each entity is different, with nonfunctional tumors being treated with traditional chemotherapy while functional tumors respond well to antihormonal therapy and immunologic agents. The conversion of one nonfunctional tumor into a functional tumor is an exceedingly rare event that complicates the overall management of these patients. In this report, we present the case of a 73-year-old woman who developed the conversion from a nonfunctional into a functional tumor and discuss the management options considered.

Metastatic insulinoma: exploration from clinicopathological signatures and genetic characteristics

Background

Insulinoma is a rare type of pancreatic neuroendocrine tumor with low incidence and low-malignant features. While very few insulinomas present with malignant behaviours, such as lymph node and liver metastasis, only a few studies have focused on this field owing to the limitation of samples. Existing evidence suggests that metastatic insulinoma largely derive from non-functional pancreatic neuroendocrine tumor. However, we found a portion of metastatic insulinomas may derive from non-metastatic insulinomas and explored their clinicopathological signatures and genetic characteristics.

Methods

Four metastatic insulinoma patients with synchronous liver metastasis or lymph node metastasis at the Peking Union Medical College Hospital between October 2016 and December 2018 were enrolled, and whole exon and genome sequencing were performed on fresh frozen tissues and peripheral blood samples. Clinicopathological information and genomic sequencing results were collected and matched to explore the characteristics of the metastatic insulinomas.

Results

These four metastatic insulinoma patients underwent surgery or interventional therapy, and their blood glucose levels immediately increased and maintained within standard range after treatment. For these four patients, the proinsulin/insulin molar ratio <1 and primary tumors were all present as PDX1+, ARX-, and insulin+, which were similar to non-metastatic insulinomas. However, the liver metastasis showed PDX1+ and ARX+, insulin+. Meanwhile, genomic sequencing data showed no recurrently mutations and typical CNV patterns. However, one patient harboured the YY1 T372R mutation, a recurrently mutated gene in non-metastatic insulinomas.

Conclusions

A portion of metastatic insulinomas were largely derived from non-metastatic insulinomas in hormone secretion and ARX/PDX1 expression patterns. Meanwhile, the accumulation of ARX expression may be involved in the progression of metastatic insulinomas.

Epidemiological trends for functional pancreatic neuroendocrine tumors: A study combining multiple imputation with age adjustment

Purpose

The purpose of this study was to examine trends in the incidence and incidence-based (IB) mortality of functional pancreatic neuroendocrine tumors(F-PNETs), and to identify factors associated with survival times.

Methods

Data were obtained from the Surveillance, Epidemiology, and End Results database from 2000 to 2017. Trends in the age-adjusted incidence of F-PNETs and IB mortality were examined using the Joinpoint Regression Program. Statistical analyses were run using chi-square tests, Kaplan-Meier curves, and the Cox proportional hazards model. Multiple imputation was used to deal with missing data.

Results

A total of 142 patients with F-PNETs met the study inclusion criteria. It was found that the incidence of F-PNETs decreased over the study period, with an annual percent change (APC) of -2. 5% (95% CI [-4. 3, -0. 5], P<0. 05). This decrease was found to be significant for women, and also when limited to cases with distant disease or rare F-PNETs, with APCs of -4. 2% (95% CI [-7. 4, -0. 9], P<0. 05), -6. 7% (95% CI [-10. 4, -2. 8], P<0. 05), and -9. 1% (95% CI [-13. 5, -4. 4], P<0. 05), respectively. The Cox regression analysis revealed that the tumor size, tumor stage, tumor type, and surgical resection were associated with F-PNETs mortality.

Conclusions

This was the first population-based epidemiological study of F-PNETs and we found a continual decrease in the incidence of F-PNETs from 2000 to 2017. The prognosis and survival times were closely related to the calendar year at diagnosis, tumor stage, and tumor size.

Comparison Between Sporadic and Multiple Endocrine Neoplasia Type 1-Associated Insulinoma

BACKGROUND

The differences between sporadic and multiple endocrine neoplasia type 1 (MEN-1)-associated insulinoma are not well described. Herein, we compared demographics, neoplasm characteristics, presentation, and survival in patients with sporadic vs MEN-1 insulinomas including benign and malignant disease.

STUDY DESIGN

A retrospective study identified insulinoma patients. MEN-1 was defined based on genetic testing or clinically in patients with 2 or more primary MEN-1 tumor types.

RESULTS

A total of 311 patients were identified: 84% benign and 16% malignant. The incidence of malignancy was similar (18% vs 16%, MEN-1 vs sporadic, p = 0.76). Within malignant patients, the median (interquartile range) age was 33 (25 ,44) years in MEN-1 vs 54 (41, 70) years in sporadic insulinoma (p = 0.04). There was no difference in sex or tumor size between MEN-1 and sporadic malignant insulinoma (p &gt; 0.05). Of the 260 patients with benign insulinoma, 7% had MEN-1 syndrome. MEN-1 patients presented with insulinoma at a younger age: median (interquartile range) age was 38 (24, 49) years vs 52 (43, 65) years (p &lt; 0.01). Resection of benign insulinoma was performed in 78% of the MEN-1 and 94% of the sporadic group (p = 0.03). Resected benign tumors were larger in the MEN-1 group: 2.0 (1.65, 2.45) cm vs 1.5 (1.2, 2.0) cm, respectively (p = 0.03). Concurrent insulinomas were more common in MEN-1 (17% vs 2%; p &lt; 0.01).

CONCLUSIONS

MEN-1 patients present with insulinoma at younger age and have larger benign pancreatic lesions at the time of resection compared with sporadic neoplasms. Younger patients and those with multifocal pancreatic neuroendocrine tumor in the setting of endogenous hyperinsulinism should be evaluated for MEN-1.

Metastatic insulinoma presenting after bariatric surgery in a patient diagnosed with MEN1

Insulinomas are uncommon neuroendocrine tumors and metastatic disease is extremely rare. We report a patient with metastatic insulinoma associated with multiple endocrine neoplasia type 1 presenting with hypoglycemia following sleeve gastrectomy. Potential causes of hypoglycemia include dumping syndrome, noninsulinoma pancreatogenous hypoglycemia syndrome, and rarely insulinoma. MEN1‐associated insulinomas have a higher recurrence rate.

Case Report: Hypoglycemia Due to Metastatic Insulinoma in Insulin-Dependent Type 2 Diabetes Successfully Treated With 177 Lu-DOTATATE

We describe a 96-year-old man with insulin-dependent type 2 diabetes mellitus who, despite insulin cessation, presented with recurrent hypoglycemia associated with confirmed inappropriate endogenous hyperinsulinemia. ⁶⁸Ga-DOTATATE-PET/CT scans demonstrated increased uptake in the pancreatic tail with multiple large intensely active liver metastases. Liver biopsy confirmed the diagnosis of well-differentiated metastatic neuroendocrine tumor. He was unsuitable for surgical resection and long-acting somatostatin analog therapy was ineffective. Subsequent management with four cycles of Lutate [177-Lutetium-DOTA⁰-Tyr³-octreotate (¹⁷⁷Lu-DOTATATE)] resulted in resolution of hypoglycemia and ongoing clinical, biochemical, and radiological response 6 years after. This case is unique due to not only the paradoxical entity of insulinoma in insulin-dependent diabetes but also the positive sustained outcome after ¹⁷⁷Lu-DOTATATE, given that unresectable metastatic insulinoma carries a poor prognosis. We review published cases of metastatic insulinoma in patients with diabetes mellitus as well as the literature to-date investigating efficacy and safety of Lutate therapy in metastatic insulinoma.

Hepatic Artery Embolization for Palliation of Symptomatic Hypoglycemia in Patients With Hepatic Insulinoma Metastases

Context

Insulinoma is a pancreatic neuroendocrine tumor that causes hyperinsulinemic hypoglycemia. Symptomatic hypoglycemia related to hepatic insulinoma metastases may be addressed with liver-directed therapies such as hepatic artery embolization.

Objective

This work aimed to determine the safety and effectiveness of bland hepatic artery embolization (HAE) for palliation of symptomatic hypoglycemia in patients with hepatic insulinoma metastases refractory to medical management.

Methods

An institutional review board–approved retrospective review was undertaken of all patients with a tissue (n = 18) or imaging (n = 2) diagnosis of hepatic insulinoma metastases and symptomatic hyperinsulinemic hypoglycemia refractory to medical management who underwent bland HAE at a single center between January 1, 1998 and November 1, 2020. Twenty patients (10 women, 10 men; mean age, 56 years; range, 18-84 years) were identified who individually underwent 1 (n = 7), 2 (n = 5), 3 (n = 5), 4 (n = 2), or 5 (n = 1) HAEs, for an overall total of 45 HAEs. Post-HAE hypoglycemia recurrence was defined as onset of adrenergic symptoms (eg, sweating, weakness, tremor), neuroglycopenic symptoms (eg, confusion, loss of consciousness), and/or documented serum glucose of less than 50 mg/dL, in the absence of an alternative explanation. Median time to first hypoglycemia recurrence, hypoglycemia-free survival (HFS), and overall survival (OS) were calculated using Kaplan-Meier method.

Results

Before HAE, all patients experienced adrenergic or neuroglycopenic symptoms alleviated by glucose intake, and 60% (n = 12) of patients had documented serum glucose of less than 50 mg/dL within 1 week of the first treatment. Median post-HAE follow-up was 9.4 months (mean, 26 months; range, 0.1-190 months). Postprocedural hypoglycemic symptom relief after the first HAE was reported in 100% (n = 20) of patients before discharge or at follow-up. Post-HAE hypoglycemia recurrence occurred in 60% (n = 12) of patients with a median time to first hypoglycemia recurrence of 2 months (mean, 14 months; range, 0.2-60 months). After the first HAE, median HFS was 14.5 months, and median OS was 16 months. One patient experienced labile postprocedure blood glucose levels requiring intensive care unit admission for intravenous dextrose. Otherwise, no major procedure-related complications occurred.

Conclusion

Bland HAE is a safe, effective, and repeatable procedure for palliation of symptomatic hypoglycemia in patients with hepatic insulinoma metastases refractory to medical management.

Clinical Characteristics and Incidences of Benign and Malignant Insulinoma Using a National Inpatient Database in Japan

CONTEXT

Insulinoma is the most common pancreatic functional neuroendocrine neoplasm, yet little information on recent clinical practice in patients with insulinoma, especially malignant insulinoma, is available.

OBJECTIVE

This work aims to clarify the characteristics and practice patterns in patients with insulinoma using a national inpatient database.

METHODS

Using the Japanese Diagnosis Procedure Combination database, we retrospectively identified patients with insulinoma admitted between 2010 and 2018. We compared background characteristics and therapeutic interventions between patients with benign and malignant insulinoma. We also estimated the incidence of insulinoma using the number of patients with newly diagnosed insulinoma in 2012.

RESULTS

We identified 844 patients with benign insulinoma and 102 patients with malignant insulinoma. Patients with malignant insulinoma were younger (median, 55.5 vs 66.0 years, P < .001) and less likely to be female (55.9% vs 65.3%, P = .061) than patients with benign insulinoma. Analysis of therapeutic interventions revealed that patients with malignant insulinoma more frequently received medications (71.6% vs 49.6%, P < .001) but less frequently underwent pancreatic surgery (57.8% vs 72.0%, P = .003). Older patients were a smaller proportion of those undergoing surgery and a larger proportion of those managed with medications without surgery (P < .001). The incidence of insulinoma was estimated to be 3.27 (95% CI, 2.93-3.61) individuals per million Japanese adult population per year.

CONCLUSION

The present study using a nationwide database had a larger sample size than previous studies and revealed definitive differences in patient characteristics and therapeutic patterns between benign and malignant insulinoma.

Canine insulinoma as a model for human malignant insulinoma research: Novel perspectives for translational clinical studies

Insulinomas are considered rare indolent neuroendocrine neoplasms in human medicine, however when metastases occur no curative treatment is available thus, novel therapies are needed. Recently advances have been made in unraveling the pathophysiology of malignant insulinoma still major challenges hinder the development of a functional model to study them. Canine malignant insulinoma have similar recurrence and a poor prognosis as human malignant insulinoma. Additionally, both human and canine patients share extensively the same environment, tend to develop insulinoma seemingly spontaneously with an etiological role for hormones, at a similar incidence and stage of lifespan, with metastasis commonly to liver and regional lymph nodes, which are unresponsive to current therapies. However, the occurrence of metastases in dogs is as high as 95% compared with only 5-16% in human studies. From a comparative oncology perspective, the shared features with human insulinoma but higher incidence of metastasis in canine insulinoma suggests the latter as a model for human malignant insulinomas. With the common purpose of increasing survival rates of human and veterinary patients, in this review we are going to compare and analyze clinical, pathological and molecular aspects of canine and human insulinomas to evaluate the suitability of the canine model for future translational clinical studies.

Long-term morbidity and mortality in patients diagnosed with an insulinoma

OBJECTIVE

Insulinomas are rare functional pancreatic neuroendocrine tumours. As previous data on the long-term prognosis of insulinoma patients are scarce, we studied the morbidity and mortality in the Finnish insulinoma cohort.

DESIGN

Retrospective cohort study.

METHODS

Incidence of endocrine, cardiovascular, gastrointestinal and psychiatric disorders, and cancers was compared in all the patients diagnosed with an insulinoma in Finland during 1980-2010 (n = 79, including two patients with multiple endocrine neoplasia type 1 syndrome), vs 316 matched controls, using the Mantel-Haenszel method. Overall survival was analysed with Kaplan-Meier and Cox regression analyses.

RESULTS

The median length of follow-up was 10.7 years for the patients and 12.2 years for the controls. The long-term incidence of atrial fibrillation (rate ratio (RR): 2.07 (95% CI: 1.02-4.22)), intestinal obstruction (18.65 (2.09-166.86)), and possibly breast (4.46 (1.29-15.39) and kidney cancers (RR not applicable) was increased among insulinoma patients vs controls, P < 0.05 for all comparisons. Endocrine disorders and pancreatic diseases were more frequent in the patients during the first year after insulinoma diagnosis, but not later on. The survival of patients with a non-metastatic insulinoma (n = 70) was similar to that of controls, but for patients with distant metastases (n = 9), the survival was significantly impaired (median 3.4 years).

CONCLUSIONS

The long-term prognosis of patients with a non-metastatic insulinoma is similar to the general population, except for an increased incidence of atrial fibrillation, intestinal obstruction, and possibly breast and kidney cancers. These results need to be confirmed in future studies. Metastatic insulinomas entail a markedly decreased survival.

Pancreatic neuroendocrine neoplasms: Clinicopathological features and pathological staging

The nomenclature and classification of pancreatic neuroendocrine neoplasms has evolved in the last 15 years based on the advances in knowledge of the genomics, clinical behaviour and response to therapies. The current 2019 World Health Organization classification of pancreatic neuroendocrine neoplasms categorises them into three groups; pancreatic neuroendocrine tumours (PanNETs)(grade 1 grade 2, grade 3), pancreatic neuroendocrine carcinomas and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) based on the mitotic rate, Ki-67 index, morphological differentiation and/or co-existing tissue subtype. PanNETs are also classified into non-functional NET, insulinoma, gastrinoma, VIPoma, glucagonoma, somatostatinoma, ACTH-producing NET and serotonin producing NET based on hormone production and clinical manifestations. A portion of the cases were associated with genetic syndromes such as multiple neuroendocrine neoplasia 1 (MEN 1), neurofibromatosis and Von Hippel-Lindau syndrome. In view of the distinctive pathology and clinical behaviour of PanNENs, the current 8th AJCC/UICC staging system has separated prognostic staging grouping for PanNETs from the pancreatic neuroendocrine carcinomas or MiNENs. Pancreatic neuroendocrine carcinomas and MiNENs are staged according to the prognostic stage grouping for exocrine pancreatic carcinoma. The new stage grouping of PanNETs was validated to have survival curves separated between different prognostic groups. This refined histological and staging would lead to appropriate selections of treatment strategies for the patients with pancreatic neuroendocrine neoplasms.

Comparison of benign and malignant insulinoma

BACKGROUND

How malignant insulinomas present relative to benign insulinomas is unknown.

METHODS

A single-institution retrospective study identified patients with insulinoma. Malignancy was defined by distant metastases, positive lymph node(s), T stage of 4, direct invasion into surrounding peripancreatic tissue, or presence of lymphovascular invasion. Wilcoxon Rank Sum tests and Kaplan-Meier analysis were used.

RESULTS

A total of 311 patients were identified: 51 malignant and 260 benign. Patients with malignant insulinoma presented with higher levels of insulin, proinsulin, and c-peptide. Malignant lesions were larger: 4.2 ± 3.2 vs 1.8 ± 0.8 cm in benign lesions, p < 0.01. Overall survival at 5 years was 66.8% vs 95.4% for malignant and benign insulinoma respectively, p < 0.01.

CONCLUSIONS

Larger size of insulinoma and increased serum β-cell polypeptide concentrations were associated with malignancy. Malignant insulinoma has poorer survival. Further work-up to rule out malignancy may be indicated for larger pancreatic lesions and for patients with higher pre-operative insulin and pro-insulin.