Comparison of benign and malignant insulinoma

[Gastrointestinal neuroendocrine tumors: update 2024]

Gastrointestinal neuroendocrine tumours (NETs) are rare and clinically heterogeneous. From a diagnostic perspective, well-differentiated tumours must be distinguished from poorly differentiated neuroendocrine carcinomas. The disease may be associated with autonomous hormone secretion by the tumour, and the resulting syndromes are often associated with reduced survival. Somatostatin analogues form the backbone of antiproliferative and antisecretory treatment alongside local ablative procedures. In pancreatic NET, prospective studies confirm the value of specific chemotherapy, particularly in terms of higher remission rates. New tyrosine kinase inhibitors are an option for patients that have failed to respond to standard treatments. Inhibition of HIF2-alpha is an emerging effective treatment option for patients with von Hippel-Lindau-syndrome associated tumours, e.g. pancreatic NET. Radioligand therapy is an established second-line option for advanced NET of the small intestine, and recent study results support its use in pancreatic NET in earlier-line treatment. Due to the complexity of the disease, management of NET patients should be performed in close collaboration with a specialized multidisciplinary team.

Pancreatic Insulinoma Masquerading as Neurological Disease: Diagnosis and Treatment of a Rare Tumor

Insulinomas are rare functional pancreatic neuroendocrine tumors that typically manifest with classic hypoglycemic symptoms, such as diaphoresis, palpitations, and tremors. Although infrequent, neuroglycopenic symptoms associated with insulinomas have been reported, often leading to delayed diagnoses. Here, we present the case of a 31-year-old male with pancreatic insulinoma who experienced recurrent episodes of seizures and confusion preceded by diaphoresis, tremors, and palpitations. During these episodes, he was found to be hypoglycemic. Comprehensive evaluations, including brain and abdominal imaging, as well as biochemical and serological testing, were conducted. The findings confirmed a diagnosis of pancreatic insulinoma. The patient underwent surgical resection of the tumor, and a biopsy confirmed the insulinoma diagnosis. He remained asymptomatic during subsequent follow-ups.

Approach to the Patient: Insulinoma

Insulinomas are hormone-producing pancreatic neuroendocrine neoplasms with an estimated incidence of 1 to 4 cases per million per year. Extrapancreatic insulinomas are extremely rare. Most insulinomas present with the Whipple triad: (1) symptoms, signs, or both consistent with hypoglycemia; (2) a low plasma glucose measured at the time of the symptoms and signs; and (3) relief of symptoms and signs when the glucose is raised to normal. Nonmetastatic insulinomas are nowadays referred to as "indolent" and metastatic insulinomas as "aggressive." The 5-year survival of patients with an indolent insulinoma has been reported to be 94% to 100%; for patients with an aggressive insulinoma, this amounts to 24% to 67%. Five percent to 10% of insulinomas are associated with the multiple endocrine neoplasia type 1 syndrome. Localization of the insulinoma and exclusion or confirmation of metastatic disease by computed tomography is followed by endoscopic ultrasound or magnetic resonance imaging for indolent, localized insulinomas. Glucagon-like peptide 1 receptor positron emission tomography/computed tomography or positron emission tomography/magnetic resonance imaging is a highly sensitive localization technique for seemingly occult, indolent, localized insulinomas. Supportive measures and somatostatin receptor ligands can be used for to control hypoglycemia. For single solitary insulinomas, curative surgical excision remains the treatment of choice. In aggressive malignant cases, debulking procedures, somatostatin receptor ligands, peptide receptor radionuclide therapy, everolimus, sunitinib, and cytotoxic chemotherapy can be valuable options.

Peptide Receptor Radionuclide Therapy Is Effective for Clinical Control of Symptomatic Metastatic Insulinoma: A Long-Term Retrospective Analysis

Metastatic insulinoma is a rare malignant neuroendocrine tumor characterized by inappropriate insulin secretion, resulting in life-threatening hypoglycemia, which is often difficult to treat. There is currently very limited information about the efficacy of peptide receptor radionuclide therapy (PRRT) for clinical control of hypoglycemia. The aim of this long-term retrospective study was to evaluate the therapeutic efficacy of PRRT for improving hypoglycemia, to evaluate the change of medication after PRRT, and to calculate progression-free survival (PFS) and overall survival (OS). Methods: Inclusion criteria were histologically proven somatostatin receptor-positive metastatic malignant insulinoma and at least 2 cycles of [90Y]Y-DOTATOC or [177Lu]Lu-DOTATOC therapy from early 2000 to early 2022. A semiquantitative scoring system was used to quantify the severity and frequency of hypoglycemic episodes under background antihypoglycemic therapy (somatostatin analog, diazoxide, everolimus, corticosteroids): score 0, no hypoglycemic episodes; score 1, hypoglycemic events requiring additional conservative treatment with optimization of nutrition; score 2, severe hypoglycemia necessitating hospitalization and combined medication or history of hypoglycemic coma. Hypoglycemic score before and after PRRT was analyzed. Time of benefit was defined as a time range of fewer hypoglycemic episodes in the observation period than at baseline. Information on antihypoglycemic medication before and after therapy, PFS, and OS was recorded. Results: Twenty-six of 32 patients with a total of 106 [90Y]Y-DOTATOC/[177Lu]Lu-DOTATOC cycles were included. The average observation period was 21.5 mo (range, 2.3-107.4 mo). Before therapy, 81% (n = 21) of the patients had a hypoglycemia score of 2 and 19% (n = 5) had a score of 1. After PRRT, 81% of patients (n = 21) had a decreased score, and the remaining 5 patients showed a stable situation. There was temporary worsening of hypoglycemia just after injection of [90Y]Y-DOTATOC/[177Lu]Lu-DOTATOC in 19% of patients. The average time of benefit in the observation period was 17.2 mo (range, 0-70.2 mo). Antihypoglycemic medication reduction was achieved in 58% (n = 15) of patients. The median OS and PFS after the start of PRRT were 19.7 mo (95% CI, 6.5-32.9 mo) and 11.7 mo (95% CI, 4.9-18.5 mo), respectively. Conclusion: To our knowledge, our study included the largest cohort of patients with malignant insulinoma to be evaluated. Long-lasting symptom control and reduction of antihypoglycemic medications were shown in most patients after late-line PRRT.

Endoscopic ultrasound-guided radiofrequency ablation of pancreatic insulinoma: a state of the art review

INTRODUCTION

Insulinomas are the most common functional pancreatic neuroendocrine tumors (PNETs) that lead to incapacitating hypoglycemia. Guidelines recommend surgical resection as the mainstay of management. However, surgery is fraught with complications, causing significant peri/post-operative morbidity. Since insulinomas are usually benign, solitary, small (<2 cm), and do not need lymphadenectomy, hence, in this regard, endoscopic ultrasound-guided radiofrequency ablation (EUS-RFA) is now being increasingly performed, to circumvent these adverse events and impairment of pancreatic function.

AREAS COVERED

A comprehensive literature search was undertaken across various databases (PubMed/MEDLINE, Embase, Scopus), with no language restriction, for relevant articles (case series, reviews, case reports) pertaining to EUS-RFA for insulinoma and PNETs, till October 2023. In this review, we have explicated the role of EUS-RFA for insulinoma management, detailing thoroughly its mechanism of action, EUS-RFA devices with data on its safety and efficacy, and an algorithmic approach for its management.

EXPERT OPINION

EUS-RFA is being advocated as a 'mini-invasive' option with the potential to replace surgery as a first-line approach for benign, sporadic, solitary, and small (<2 cm) insulinomas. Under real-time guidance, EUS-RFA has immense precision, is safe, predictable, with acceptable safety profile. Presently, it is being frequently performed for high-risk or inoperable candidates. Current need-of-the-hour is a randomized controlled trial to substantiate its role in the therapeutic algorithm for insulinoma management.

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.

Radiofrequency Ablation of Pancreatic Solid Tumors

Today, endoscopic ultrasound-guided radiofrequency ablation has become increasingly accepted for the treatment of different precancerous and neoplastic lesions of the pancreas, particularly in patients who are unfit for surgery. However, thermal ablation has long been suspected to induce pancreatitis or to injure adjacent structures. Published case reports and case series on this topic are of limited size and are often based on a heterogeneous study population, reporting on functional and nonfunctional pancreatic neuroendocrine tumors. Nevertheless, the overall results are promising, with high technical success and relatively low complication rates.

Endoscopic Ultrasound-Guided Locoregional Treatments for Solid Pancreatic Neoplasms

Solid pancreatic neoplasms are one of the most diagnosed gastrointestinal malignancies thanks to the current and progressive advances in radiologic methods. Endoscopic ultrasound-guided techniques have over time gained a prominent role in the differential diagnosis and characterization of these pancreatic lesions, including pancreatic cancer, neuroendocrine tumors, and metastases. Recently, several endoscopic ultrasound-guided locoregional treatment techniques, which are divided into thermal ablative techniques and non-thermal injection techniques, have been developed and applied in different settings for the treatment of solid pancreatic neoplasms. The most common ablative techniques are radiofrequency, microwave, laser, photodynamic therapy and hybrid techniques such as hybrid cryothermal ablation. The most common injection techniques are ethanol injection, immunotherapy and brachytherapy. In this review, we update evidence about the efficacy and safety of endoscopic ultrasound-guided locoregional treatments for solid pancreatic neoplasms.

Clinicopathological Features of Insulinoma: A Single Tertiary Center Experience

Insulinoma is a rare pancreatic neuroendocrine tumor with an incidence of 1-4 cases per million. Here we present our 10 years of experience in 13 cases of insulinoma. We retrospectively reviewed all insulinoma patients diagnosed and treated between 2012 and 2022. Clinical and pathological features, diagnostic methods, and follow-up results of insulinoma patients were discussed. A total of 13 patients were included in this study (7 men, and 6 women). The mean age at the time of diagnosis was 58 (36.5-70.5) years. There is only one patient diagnosed with MEN-1 syndrome. The mean time from the onset of symptoms to the diagnosis was 15 (7-27.5) months. In the prolonged fasting test, symptomatic hypoglycemia occurred in all patients within 48 h. The median size of lesions was 15 (12-24) mm, and 46.2% of these lesions were isolated in the pancreatic tail. Ga-68 DOTATATE PET/CT detected lesions with 100% accuracy. Three patients met the criteria for malignant insulinoma. Octreotide LAR was given to 1 patient with metastatic disease and 1 patient who did not accept surgery. The metastatic patient received 8 cycles of Lu treatment and died after 51 months of follow-up. The diagnosis of insulinoma can be challenging. The 48-h fasting test period provided sufficient information for the diagnosis of insulinoma. Ga-68 DOTATATE PET/CT may be an alternative in cases where cross-sectional imaging cannot localize the pancreatic lesion.

A rare case of insulinoma presented with neurological manifestations: A case report

INTRODUCTION

Insulinoma is a rare, most commonly benign tumor with several manifestations that may be misattributed to psychiatric, cardiac, or neurological disorders.

CASE PRESENTATION

In this report, we describe the case of a 47-year-old woman who presented with neurological manifestations, including seizures, that were misdiagnosed initially as seizures due to small vessel ischemic disease and managed accordingly with various antiepileptic drugs without any benefit. An endocrinologist's assessment suggested measuring the levels of glucose, insulin, and C-peptide. The results were abnormal. Subsequently, an enhanced-contract CT scan followed by an MRI of the abdomen was requested, and it revealed a well-delineated lesion measuring about (3,2 × 2,1 × 2,2) cm located in the tail of the pancreas. On laparoscopic visualization, a partial pancreatectomy was accomplished using a stapler. Histopathology of the surgical specimen revealed a benign insulinoma with free margins. The follow-up after three months demonstrated that the patient was doing well.

CLINICAL DISCUSSION

Although insulinoma is mostly benign, conservative surgery such as enucleation or partial pancreatectomy is usually the cornerstone of treatment. If other indicators such as large size, multiplicity, proximity to the major pancreatic duct, association with MEN1, and malignancy were present, radical resection was considered.

CONCLUSION

A high index of suspicion is requested to establish the diagnosis of insulinoma, especially when presenting with severe neurological symptoms like seizures and coma. It should be kept in mind that insulinoma is the most common cause of hypoglycemia associated with endogenous hyperinsulinism.

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.

Case Report: Giant insulinoma, a very rare tumor causing hypoglycemia

Insulinomas, with an incidence of 4 cases per million individuals per year, remain amongst the most frequent functional neuroendocrine tumors. The usual diameter of insulinomas usually remains under 3 cm of major axis. However, 44 exceptional cases of "giant insulinomas", have been reported worldwide, generally exceeding 9 cm in major axis. In this article, we report the case of a 38-year-old woman whom suffered from chronic hypoglycemia despite treatment with diazoxide. Abdominal CT-scan revealed a 88 x 73 mm mass located at the tail of the pancreas. Following surgical excision, histopathological analysis confirmed G1 neuroendocrine tumor, with focal cytoplasmic expression of insulin in tumor cells. After a 16-month follow-up period, the patient didn't address any specific complaint, and no disease recurrence and/or metastasis were observed. A ⁶⁸Ga-DOTATATE-PET scan was performed 6 months after surgery, which came back normal. Genetic evaluation has not been performed in our patient. The physiopathology of giant insulinomas remain unexplained, however with possible relationship with type 1 multiple endocrine neoplasia, sporadic somatic YY1 mutations and possible transformation of bulky non-functional pancreatic neuroendocrine tumors to a functional phenotype, with slow insulin secretion. While giant insulinomas remain rare in the literature, multicentric genetic analysis of tumor samples might reveal unique features of this rare subtype of neuroendocrine pancreatic tumors. Insulinomas of large size tend to have greater malignancy and higher rates of invasiveness. Careful follow-up, especially for liver and lymph node metastases, must be performed using functional imaging techniques to avoid disease relapse.

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.

Malignant insulinoma: Can we predict the long-term outcomes?

Insulinomas are the most frequent type of functional pancreatic neuroendocrine tumors with a variety of neuroglycopenic and autonomic symptoms and well-defined diagnostic criteria; however, prediction of their clinical behavior and early differentiation between benign and malignant lesions remain a challenge. The comparative studies between benign and malignant cases are limited, suggesting that short clinical history, early hypoglycemia during fasting, high proinsulin, insulin, and C-peptide concentrations raise suspicion of malignancy. Indeed, malignant tumors are larger with higher mitotic count and Ki-67 proliferative activity, but there are no accurate histological criteria to distinguish benign from malignant forms. Several signaling pathways have been suggested to affect the pathophysiology and behavior of insulinomas; however, our knowledge is limited, urging a further understanding of molecular genetics. Therefore, there is a need for the identification of reliable markers of metastatic disease that could also serve as therapeutic targets in patients with malignant insulinoma. This opinion review reflects on current gaps in diagnostic and clinical aspects related to the malignant behavior of insulinoma.

EUS-guided radiofrequency ablation for pancreatic insulinoma: experience in 2 tertiary centers

BACKGROUND AND AIMS

Insulinoma is the most frequent functional neuroendocrine tumor of the pancreas, and preserving surgery is the treatment of choice. EUS-guided radiofrequency ablation (EUS-RFA) is a novel and promising technique that induces tissue necrosis of localized lesions. This article presents a preliminary clinical experience in treating pancreatic insulinomas <2 cm by EUS-RFA, focusing on safety and efficacy.

METHODS

The clinical course of patients with pancreatic insulinoma treated by EUS-RFA at 2 tertiary referral centers was analyzed.

RESULTS

Between November 2017 and December 2020, 7 patients were included (6 women; mean age, 66 years). EUS-RFA was feasible in all patients with immediate hypoglycemia relief after only 1 single treatment session; 6 of 7 achieved complete response by cross-sectional imaging and remained asymptomatic (median follow-up, 21 months; range, 3-38). Three patients had minor adverse events. One elderly patient developed a large retrogastric collection 15 days after treatment and died 1 month after EUS-RFA.

CONCLUSIONS

Management of pancreatic neuroendocrine tumors <2 cm by EUS-RFA seems to be effective with an acceptable safety profile. However, further evidence focusing on long-term survival and recurrence is needed.

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.