Insulinomatosis: a multicentric insulinoma disease that frequently causes early recurrent hyperinsulinemic hypoglycemia

[Multiple neuroendocrine tumors of the pancreas]

Multiple neuroendocrine tumors (NET) of the pancreas often have a hereditary background. Sporadic and hereditary NET do not differ morphologically or with regard to their hormone expression. The most important clues for a hereditary background are provided by examination of the peritumoral pancreatic tissue, especially the morphology and hormone expression of the endocrine islets. Hyperplastic or dysplastic islets and microtumors with aberrant distribution of insulin and glucagon are the main features of hereditary NET. Morphological diagnosis of potentially hereditary NET has a relevant impact on the prognosis and clinical care of patients.

Case report: Insulinomatosis: description of four sporadic cases and review of the literature

The best-known etiologies of hyperinsulinemic hypoglycemia are insulinoma, non-insulinoma pancreatogenous hypoglycemic syndrome, autoimmune processes, and factitious hypoglycemia. In 2009, a disease not associated with classic genetic syndromes and characterized by the presence of multiple pancreatic lesions was described and named insulinomatosis. We present the clinical and pathologic features of four patients with the diagnosis of insulinomatosis, aggregated new clinical data, reviewed extensively the literature, and illustrated the nature and evolution of this recently recognized disease. One of our patients had isolated (without fasting hypoglycemia) postprandial hypoglycemia, an occurrence not previously reported in the literature. Furthermore, we reported the second case presenting malignant disease. All of them had persistent/recurrent hypoglycemia after the first surgery even with pathology confirming the presence of a positive insulin neuroendocrine tumor. In the literature review, 27 sporadic insulinomatosis cases were compiled. All of them had episodes of fasting hypoglycemia except one of our patients. Only two patients had malignant disease, and one of them was from our series. The suspicion of insulinomatosis can be raised before surgery in patients without genetic syndromes, with multiple tumors in the topographic investigation and in those who had persistent or recurrent hypoglycemia after surgical removal of one or more tumors. The definitive diagnosis is established by histology and immunohistochemistry and requires examination of the "macroscopically normal pancreas." Our case series reinforces the marked predominance in women, the high frequency of recurrent hypoglycemia, and consequently, a definitive poor response to the usual surgical treatment.

Changes in diagnosis and operative treatment of insulinoma over two decades

PURPOSE

Most insulinomas are small solitary, benign neoplasms. Imaging and surgical techniques improved over the last 20 years. Thus, the aim of the present study was to analyze changes in diagnosis and surgery of insulinoma patients in a referral center over two decades.

METHODS

Operated patients with a histologically proven insulinoma were retrieved from a prospective database. Clinico-pathological characteristics and outcomes were retrospectively analyzed with regard to the time periods 2000-2010 (group 1) and 2011-2020 (group 2).

RESULTS

Sixty-one of 202 operated patients with pNEN had an insulinoma, 37 (61%) in group 1 and 24 (39%) in group 2. Of those 61 insulinomas, 49 (80%) were sporadic benign, 8 (13%) benign MEN1-associated insulinomas, and 4 (7%) sporadic malignant insulinomas. In 35 of 37 (95%) patients of group 1 and all patients of group 2, the insulinoma was preoperatively identified by imaging. The most sensitive imaging modality was endoscopic ultrasound (EUS) with correctly diagnosed and localized insulinomas in 89% of patients in group 1 and 100% in group 2. In group 1, significantly less patients were operated via minimally invasive approach compared to group 2 (19% (7/37) vs. 50% (12/24), p = 0.022). Enucleation was the most frequently performed operation (31 of 61, 51%), followed by distal resection (15 of 61, 25%) without significant differences between groups 1 and 2. The rate of relevant postoperative complications was not different between groups 1 and 2 (24% vs. 21%, p = 0.99). Two patients with benign insulinoma (1 out of each group) experienced disease recurrence and underwent a second resection. After a median follow-up of 134 (1-249) months, however, all 57 (100%) patients with benign insulinoma and 3 out of 4 patients with malignant insulinoma had no evidence of disease.

CONCLUSION

Insulinoma can be preoperatively localized in almost all patients, allowing for a minimally invasive, parenchyma-sparing resection in selected patients. The long-term cure rate is excellent.

Neuroendocrine neoplasms in the context of inherited tumor syndromes: a reappraisal focused on targeted therapies

PURPOSE

Neuroendocrine neoplasms can occur as part of inherited disorders, usually in the form of well-differentiated, slow-growing tumors (NET). The main predisposing syndromes include: multiple endocrine neoplasias type 1 (MEN1), associated with a large spectrum of gastroenteropancreatic and thoracic NETs, and type 4 (MEN4), associated with a wide tumour spectrum similar to that of MEN1; von Hippel-Lindau syndrome (VHL), tuberous sclerosis (TSC), and neurofibromatosis 1 (NF-1), associated with pancreatic NETs. In the present review, we propose a reappraisal of the genetic basis and clinical features of gastroenteropancreatic and thoracic NETs in the setting of inherited syndromes with a special focus on molecularly targeted therapies for these lesions.

METHODS

Literature search was systematically performed through online databases, including MEDLINE (via PubMed), and Scopus using multiple keywords' combinations up to June 2022.

RESULTS

Somatostatin analogues (SSAs) remain the mainstay of systemic treatment for NETs, and radiolabelled SSAs can be used for peptide-receptor radionuclide therapy for somatostatin receptor (SSTR)-positive NETs. Apart of these SSTR-targeted therapies, other targeted agents have been approved for NETs: the mTOR inhibitor everolimus for lung, gastroenteropatic and unknown origin NET, and sunitinib, an antiangiogenic tyrosine kinase inhibitor, for pancreatic NET. Novel targeted therapies with other antiangiogenic agents and immunotherapies have been also under evaluation.

CONCLUSIONS

Major advances in the understanding of genetic and epigenetic mechanisms of NET development in the context of inherited endocrine disorders have led to the recognition of molecular targetable alterations, providing a rationale for the implementation of treatments and development of novel targeted therapies.

Complete remission of recurrent multiple insulin-producing neuroendocrine tumors of the pancreas with somatostatin analogs: a case report and literature review

Hyperinsulinemic hypoglycemia is most commonly caused by a single, sporadic insulinoma. Multicentric insulinoma disease (insulinomatosis) as well as metachronous neuroendocrine tumors of the pancreas, known also as neuroendocrine adenomatosis, represent a very rare condition, if not associated with multiple endocrine neoplasia type 1 syndrome (MEN1) or Von Hippel Lindau disease. We report a 9-year follow-up of a 41-year-old woman, initially presenting with hypoglycemic syndrome caused by two insulin-producing tumors, who underwent subtotal pancreasectomy in 2012, with histology compatible with multiple small neuroendocrine tumors. An approximately 1-cm insulin-producing tumor recurred at subsequent biochemical and radiological follow-up, and was cured with the somatostatin analog octreotide as a single treatment, until remission of symptoms and complete regression of the pancreatic lesion achieved after only 16 months of treatment. The possible mechanisms for these findings are discussed and the literature is briefly reviewed.

Second MAFA Variant Causing a Phosphorylation Defect in the Transactivation Domain and Familial Insulinomatosis

Adult-onset familial insulinomatosis is a rare disorder with recurrent, severe hypoglycemia caused by multiple insulin-secreting pancreatic tumors. The etiology was unclear until the variant p.Ser64Phe in the transcription factor MAFA, a key coordinator of β-cell insulin secretion, was defined as the cause in two families. We here describe detailed genetic, clinical, and family analyses of two sisters with insulinomatosis, aiming to identify further disease causes. Using exome sequencing, we detected a novel, heterozygous missense variant, p.Thr57Arg, in MAFA’s highly conserved transactivation domain. The impact of the affected region is so crucial that in vitro expression studies replacing Thr57 have already been performed, demonstrating a phosphorylation defect with the impairment of transactivation activity and degradation. However, prior to our study, the link to human disease was missing. Furthermore, mild hyperglycemia was observed in six additional, heterozygote family members, indicating that not only insulinomatosis but also MODY-like symptoms co-segregate with p.Thr57Arg. The pre-described MAFA variant, p.Ser64Phe, is located in the same domain, impairs the same phosphorylation cascade, and results in the same symptoms. We confirm MAFA phosphorylation defects are important causes of a characteristic syndrome, thus complementing the pathophysiological and diagnostic disease concept. Additionally, we verify the high penetrance and autosomal dominant inheritance pattern.

Pancreatic Neuroendocrine Neoplasms: Updates on Genomic Changes in Inherited Tumour Syndromes and Sporadic Tumours Based on WHO Classification

Pancreatic neuroendocrine neoplasms (PanNENs) are the neuroendocrine neoplasms with greatest rate of increase in incidence. Approximately 10% of PanNENs arise as inherited tumour syndromes which include multiple endocrine neoplasia type 1, multiple endocrine neoplasia type 4, von Hippel-Lindau syndrome, neurofibromatosis type1, tuberous sclerosis complex 1/2, Cowden syndrome, and Glucagon cell hyperplasia and neoplasia as well as familial insulinomatosis. In sporadic PanNENs, driver mutations in MEN1, DAXX/ATRX and mTOR pathway genes are associated with development and progression in pancreatic neuroendocrine tumours. The other changes are in VEGF pathway, Notch pathway, germline mutations in MUTYH, CHEK2, BRCA2, PHLDA3 as well as other genetic alterations. On the other hand, pancreatic neuroendocrine carcinomas share similar genetic alterations with ductal adenocarcinomas, e.g., TP53, RB1 or KRAS. In addition, microRNA and changes in immune microenvironment were noted in PanNENs. Updates on these genetic knowledges contribute to the development of management strategies for patients with PanNENs.

Overview of the 2022 WHO Classification of Familial Endocrine Tumor Syndromes

This review of the familial tumor syndromes involving the endocrine organs is focused on discussing the main updates on the upcoming fifth edition of the WHO Classification of Endocrine and Neuroendocrine Tumors. This review emphasizes updates on histopathological and molecular genetics aspects of the most important syndromes involving the endocrine organs. We describe the newly defined Familial Cancer Syndromes as MAFA-related, MEN4, and MEN5 as well as the newly reported pathological findings in DICER1 syndrome. We also describe the updates done at the new WHO on the syndromic and non-syndromic familial thyroid diseases. We emphasize the problem of diagnostic criteria, mention the new genes that are possibly involved in this group, and at the same time, touching upon the role of some immunohistochemical studies that could support the diagnosis of some of these conditions. As pathologists play an important role in identifying tumors within a familial cancer syndrome, we highlight the most important clues for raising the suspicious of a syndrome. Finally, we highlight the challenges in defining these entities as well as determining their clinical outcome in comparison with sporadic tumors. Instead of the usual subject review, we present the highlights of the updates on familial cancer syndromes by answering select questions relevant to practicing pathologists.

Adult Proinsulinomatosis Associated With a MAFA Germline Mutation as a Rare Cause of Recurrent Hypoglycemia

Sporadic adult insulinomatosis is an extremely rare clinical condition. Adult proinsulinomatosis has not yet been described. We report the case of a 48-year-old female patient with recurrent hypoglycemia caused by benign proinsulin-secreting pancreatic neuroendocrine neoplasias (pNENs) with no history of multiple endocrine neoplasia type 1. Initial workup revealed elevated serum proinsulin levels and a positive fasting test. Magnetic resonance imaging and endosonography visualized 2 pNENs in the pancreatic body and tail that were treated by robotic-assisted enucleation. After initial biochemical cure, the patient's hypoglycemia recurred 3 months after surgery. Imaging showed a new lesion in the pancreatic body, so that now a spleen-preserving subtotal distal pancreatectomy was performed. The pathological examination revealed 17 neuroendocrine microadenomas and 1 well-differentiated pNEN (Ki-67% 1%-2%) of 22-mm size as well as more than 200 (pro)insulin-producing β-cell precursor lesions, confirming the diagnosis of adult proinsulinomatosis. Mutation analysis of the germline DNA identified the in-frame deletion mutation (p.His207del) in the MAFA gene on chromosome 8. The patient was biochemically cured 16 months after the last surgical resection. Similarly to adult insulinomatosis, the presence of proinsulin-secreting tumors causes recurrent hypoglycemia and might be associated with germline mutations in the MAFA gene.

Pancreatic Neuroendocrine Neoplasms: Landscape and Horizon

CONTEXT.—

Since the initial description of pancreatic endocrine physiology and the recognition of islet cell tumors in the 1800s, there have been noteworthy advances in the pathobiology of pancreatic neuroendocrine neoplasms (PanNENs), and definition of the important distinction between well-differentiated neuroendocrine tumor (PanNET) and poorly differentiated neuroendocrine carcinoma (PanNEC). The evolving knowledge has resulted in a continuous update in terminology, classification, and grading system for this group of neoplasms. Pancreatic neuroendocrine tumors associated with hereditary conditions have been linked to unique molecular and genetic events, and sporadic PanNETs have specific gene signatures. Based on accumulative experience and knowledge, therapeutic strategies have been defined for this group of neoplasms.

OBJECTIVE.—

To review the evolution and description of the pathologic-genomic evolution of PanNENs, and to facilitate accurate pathologic interpretation for the corresponding clinical management.

DATA SOURCES.—

Literature review of published studies and author's own work.

CONCLUSIONS.—

Evolving experience and knowledge have established subtypes of pancreatic neuroendocrine neoplasms, based on their genotype and phenotype. Accurate pathologic interpretation of the specific neoplasm has significant implications for therapy and prognosis.

New therapies for patients with multiple endocrine neoplasia type 1

In 1953, for the first time, Paul Wermer described a family presenting endocrine gland neoplasms over several generations. The transmission was autosomal dominant and the penetrance was high. Forty years later in 1997, the multiple endocrine neoplasia type 1 (MEN1) gene was sequenced, thus enabling diagnosis and early optimal treatment. Patients carrying the MEN1 gene present endocrine but also non-endocrine tumors. Parathyroid, pancreatic and pituitary impairment are the three main types of endocrine involvement. The present article details therapeutic management of hyperparathyroidism, neuroendocrine pancreatic tumors and pituitary adenomas in patients carrying the MEN1 gene. Significant therapeutic progress has in fact been made in the last few years. As concerns the parathyroid glands, screening of family members and regular monitoring of affected subjects now raise the question of early management of parathyroid lesions and optimal timing of parathyroid surgery. As concerns the duodenum-pancreas, proton-pump inhibitors are able to control gastrin-secreting syndrome, reducing mortality in MEN1 patients. Mortality in MEN1 patients is no longer mainly secondary to uncontrolled hormonal secretion but to metastatic (mainly pancreatic) disease progression. Tumor risk requires regular monitoring of morphological assessment, leading to iterative pancreatic surgery in a large number of patients. Finally, pituitary adenomas in MEN1 patients are traditionally described as aggressive, invasive and resistant to medical treatment. However, regular pituitary screening showed them to be in fact infra-centimetric and non-secreting in the majority of patients. Consequently, it is necessary to regularly monitor MEN1 patients, with regular clinical, biological and morphological work-up. Several studies showed that this regular monitoring impairs quality of life. Building a relationship of trust between patients and care provider is therefore essential. It enables the patient to be referred for psychological or psychiatric care in difficult times, providing long-term support and preventing any breakdown in continuity of care.

A case of insulinoma diagnosed postpartum with hypoglycemic symptoms that were masked during pregnancy

The diagnosis of insulinoma in perinatal women can be difficult, as hypoglycemic symptoms may be masked by pregnancy-associated insulin resistance. In addition, when multiple insulinomas are observed, it is necessary to consider the possibility not only of MEN1, but also of insulinomatosis.

Molecular Pathology of Well-Differentiated Gastro-entero-pancreatic Neuroendocrine Tumors

Well differentiated neuroendocrine tumors (NETs) arising in the gastrointestinal and pancreaticobiliary system are the most common neuroendocrine neoplasms. Studies of the molecular basis of these lesions have identified genetic mutations that predispose to familial endocrine neoplasia syndromes and occur both as germline events and in sporadic tumors. The mutations often involve epigenetic regulators rather than the oncogenes and tumor suppressors that are affected in other malignancies. Somatic copy number alterations and miRNAs have also been implicated in the development and progression of some of these tumors. The molecular profiles differ by location, but many are shared by tumors in other sites, including those outside the gastroenteropancreatic system. The approach to therapy relies on both the neuroendocrine nature of these tumors and the identification of specific alterations that can serve as targets for precision oncologic approaches.

New Regions With Molecular Alterations in a Rare Case of Insulinomatosis: Case Report With Literature Review

Insulinomatosis is characterized by monohormonality of multiple macro-tumors and micro-tumors that arise synchronously and metachronously in all regions of the pancreas, and often recurring hypoglycemia. One of the main characteristics of insulinomatosis is the presence of insulin-expressing monohormonal endocrine cell clusters that are exclusively composed of proliferating insulin-positive cells, are less than 1 mm in size, and show solid islet-like structure. It is presumed that insulinomatosis affects the entire population of β-cells. With regards to molecular genetics, this phenomenon is not related to mutation in MEN1 gene and is more similar to sporadic benign insulinomas, however, at the moment molecular genetics of this disease remains poorly investigated. NGS sequencing was performed with a panel of 409 cancer-related genes. Results of sequencing were analyzed by bioinformatic algorithms for detecting point mutations and copy number variations. DNA copy number variations were detected that harbor a large number of genes in insulinoma and fewer genes in micro-tumors. qPCR was used to confirm copy number variations at ATRX, FOXL2, IRS2 and CEBPA genes. Copy number alterations involving FOXL2, IRS2, CEBPA and ATRX genes were observed in insulinoma as well as in micro-tumors samples, suggesting that alterations of these genes may promote malignization in the β-cells population.

Surgery for multiple endocrine neoplasia type 1-related insulinoma: long-term outcomes in a large international cohort

Background

Insulinomas are found in 10–15 per cent of patients with multiple endocrine neoplasia type 1 (MEN1) and lead to life‐threatening hypoglycaemia. Surgical outcome and the optimal surgical strategy for MEN1‐related insulinoma are unknown.

Methods

Patients with MEN1‐related insulinomas were identified in 46 centres in Europe and North America between 1990 and 2016. Insulinomas were considered localized if the lesion was in the pancreatic head or body/tail. Patients with pancreatic neuroendocrine tumours throughout the pancreas were suspected of having multifocal insulinoma. The primary outcome was postoperative hypoglycaemia, defined as persistent hypoglycaemia, or recurrent hypoglycaemia caused by a new insulinoma or insulin‐producing liver metastases. Hypoglycaemia‐free survival was estimated by the Kaplan–Meier method.

Results

Ninety‐six patients underwent resection for MEN1‐related insulinoma. Sixty‐three and 33 patients had localized and multifocal insulinomas respectively. After a median follow‐up of 8 (range 1–22) years, one patient (1 per cent) had persistent disease and six (6 per cent) had developed recurrent disease, of whom four had a new insulinoma. The 10‐year hypoglycaemia‐free survival rate was 91 (95 per cent c.i. 80 to 96) per cent. Of those with localized disease, 46 patients underwent pancreatic resection and 17 enucleation. One of these patients had persistent disease and one developed recurrent insulinoma. Among patients with multifocal disease, three developed new insulinomas and two developed insulin‐producing liver metastases.

Conclusion

Surgery for MEN1‐related insulinoma is more successful than previously thought.

[Inherited tumor syndromes of gastroenteropancreatic and thoracic neuroendocrine neoplasms]

About 5% of gastroenteropancreatic and thoracic neuroendocrine neoplasms (NENs) arise in the context of an inherited tumour syndrome. The two most frequent syndromes are: multiple endocrine neoplasia type 1 (MEN1), associated with a large spectrum of endocrine and non endocrine tumours, including duodenopancreatic, thymic and bronchial NENs, and the von Hippel-Lindau syndrome VHL, associated with pancreatic NENs. Two inherited syndromes have a low incidence of NENs: neurofibromatosis type 1 (NF1), associated with duodenal somatostatinomas, and tuberous sclerosis (TSC), associated with pancreatic NENs. Two rare syndromes have a high incidence of NENs: multiple endocrine neoplasia type 4 (MEN4), with a tumour spectrum similar to that of MEN1, and glucagon cell hyperplasia neoplasia (GCHN), involving only the pancreas. It is likely that other syndromes remain to be characterized, especially in familial small-intestinal NENs. The diagnosis is usually raised because of the suggestive clinical setting: young age at diagnosis, multiple tumours in multiple organs, familial history. Except in VHL and NF1, tumours themselves do not show specific pathological features; they usually are well differentiated and of low histological grade; their prognosis is good, except for MEN1-associated thymic NENs. The most suggestive pathological feature is their combination with various endocrine and/or non endocrine lesions in the adjacent tissue. Pathological examination is important, for a correct diagnosis and for an accurate management of the patients and their families, who must be referred to expert centers.

A semicentennial of pancreatic pathology: the genetic revolution is here, but don't throw the baby out with the bath water!

The last 50 years have witnessed an explosion in our understanding of the pathology of pancreatic diseases. Entities known to exist 50 years ago have been defined more precisely and are now better classified. New entities, previously not recognized, have been discovered and can now be treated. Importantly, new tools have been developed that have unraveled the fundamental biological drivers of a number of pancreatic diseases. Many of these same tools have also been applied clinically, supplementing the tried and true hematoxylin and eosin stained slide with a plethora of new, highly sensitive and specific tests that improve diagnostic accuracy and delineate best treatments. As exciting as these many advances are, our knowledge of pancreatic pathology remains incomplete, and there is much to be learned.

Patient characteristics and clinical outcomes following initial surgical intervention for MEN1 associated pancreatic neuroendocrine tumours: A systematic review and exploratory meta-analysis of the literature

BACKGROUND

This systematic review aimed to define the outcomes of different pancreatic resection procedures for multiple endocrine neoplasia type 1 (MEN1) associated pancreatic neuroendocrine neoplasms (pNENs).

METHODS

A search of PubMed, MEDLINE and SCOPUS databases were performed in accordance with PRISMA guidelines.

RESULTS

Twenty-seven studies including 533 patients undergoing initial pancreatic resection for MEN1 associated pNENs were included in this systematic review. Three hundred and sixty-six (68.7%) distal pancreatectomies (DP), 120 (22.5%) sole enucleations (SE) and 47 (8.8%) pancreaticoduodenectomies (PD) were identified. SE was associated with a higher rate of recurrence than DP (25/67, 37% vs 40/190, 21% respectively, P = 0.008) but a lower rate of endocrine insufficiency than PD (1/20, 5% vs 8/21, 38% respectively, P = 0.010). A meta-analysis of major pancreatic resections (PD or DP) vs SE in 15 studies showed that SE is associated with an increased rate of recurrence (Major resection 42/184, 23% vs SE 20/53, 38% RR 0.65 CI 0.43-0.96 P = 0.032) but reduced rate of postoperative endocrine insufficiency (Resection 37/93, 40% vs SE 0/24, 0% RR 7.37 CI 1.57-34.64 P = 0.008). Similarly, insulinomas and functional pNENs overall had lower rates of recurrence and reoperation with major resection. There was no difference in the reoperation rates or survival outcomes after SE compared with major pancreatic resections at follow-up (pooled overall mean duration: 85 months).

CONCLUSION

Major pancreatic resections for MEN1 associated pNENs have a lower risk of recurrence and a higher risk of postoperative endocrine insufficiency when compared to sole enucleation, but a similar rate of reoperation and survival.

Black swans - neuroendocrine tumors of rare locations

Neuroendocrine neoplasms (NEN) are rare and heterogeneous. Therefore, they often remain unrecognized for many years, causing significant disease burden. We here report on four unusual NEN presentations including a metastatic NEN of the kidney, hypoglycemia caused by an insulin-like growth factor-2-oma (previously called non-islet-cell tumor hypoglycemia), multifocal pheochromocytoma in von Hippel Lindau syndrome, and ileal NEN metastatic to the heart. One could say that each one of these tumors were "black swans" and learning about them will increase further awareness of the spectrum of NEN.

Insulinoma: A retrospective study analyzing the differences between benign and malignant tumors

BACKGROUND/OBJECTIVES

Insulinoma is a rare pancreatic tumor and, usually, a benign disease but can be a malignant one and, sometimes, a highly aggressive disease. The aim of this study was to determine differences between benign and malignant tumors.

METHODS

Retrospective study of 103 patients with insulinoma treated in a tertiary center. It was analyzed demographic, clinical, laboratory, localization and histologic analysis of tumor and follow up data of subjects in order to identify differences between individuals benign and malignant disease.

RESULTS

Almost all patients (87%) had a benign tumor and survival rates of 100% following pancreatic tumor surgery. Those with malignant tumors (13%) have a poor prognosis, 77% insulinoma-related deaths over a period of 1-300 months after the diagnosis with a survival rate of 24% in five years. The following factors are associated with an increased risk of malignant disease: duration of symptoms < 24 months, fasting time for the occurrence of hypoglycemia < 8 h, blood plasma insulin concentration ≥ 28 μU/mL and C-peptide ≥ 4.0 ng/mL at the glycemic nadir and tumor size ≥ 2.5 cm.

CONCLUSIONS

Our data help to base the literature about these tumors, reinforcing that although insulinoma is usually a single benign and surgically treated neoplasia, the malignant one is difficult to treat. We highlight the data that help predict a malignancy behavior of tumor and suggest a long follow up after diagnosis in these cases.

MAFA missense mutation causes familial insulinomatosis and diabetes mellitus

We report a disease-causing mutation in the β-cell–enriched MAFA transcription factor. Strikingly, the missense p.Ser64Phe MAFA mutation was associated with either of two distinct phenotypes, multiple insulin-producing neuroendocrine tumors of the pancreas—a condition known as insulinomatosis—or diabetes mellitus, recapitulating the physiological properties of MAFA both as an oncogene and as a key islet β-cell transcription factor. The implication of MAFA in these human phenotypes will provide insights into how this transcription factor regulates human β-cell activity as well as into the mechanisms of Maf-induced tumorigenesis.

The β-cell–enriched MAFA transcription factor plays a central role in regulating glucose-stimulated insulin secretion while also demonstrating oncogenic transformation potential in vitro. No disease-causing MAFA variants have been previously described. We investigated a large pedigree with autosomal dominant inheritance of diabetes mellitus or insulinomatosis, an adult-onset condition of recurrent hyperinsulinemic hypoglycemia caused by multiple insulin-secreting neuroendocrine tumors of the pancreas. Using exome sequencing, we identified a missense MAFA mutation (p.Ser64Phe, c.191C>T) segregating with both phenotypes of insulinomatosis and diabetes. This mutation was also found in a second unrelated family with the same clinical phenotype, while no germline or somatic MAFA mutations were identified in nine patients with sporadic insulinomatosis. In the two families, insulinomatosis presented more frequently in females (eight females/two males) and diabetes more often in males (12 males/four females). Four patients from the index family, including two homozygotes, had a history of congenital cataract and/or glaucoma. The p.Ser64Phe mutation was found to impair phosphorylation within the transactivation domain of MAFA and profoundly increased MAFA protein stability under both high and low glucose concentrations in β-cell lines. In addition, the transactivation potential of p.Ser64Phe MAFA in β-cell lines was enhanced compared with wild-type MAFA. In summary, the p.Ser64Phe missense MAFA mutation leads to familial insulinomatosis or diabetes by impacting MAFA protein stability and transactivation ability. The human phenotypes associated with the p.Ser64Phe MAFA missense mutation reflect both the oncogenic capacity of MAFA and its key role in islet β-cell activity.

Hormone secreting gastro-entero-pancreatic neuroendocrine neoplasias (GEP-NEN): When to consider, how to diagnose?

Neuroendocrine neoplasms of the digestive system (GEP-NEN) represent a heterogeneous group of malignancies with various clinical presentation and prognosis. GEP-NENs can potentially affect all organs of the gastrointestinal tract; characteristically they share the biological property to produce and secrete peptides and neuroamines. About 30% of GEP-NENs are hormonally active and can cause specific clinical syndromes. The clinical presentation mainly depends on the primary site of the tumor and its functionality. Because of the wide spectrum of clinical symptoms and their misperceived rarity, diagnosis of GEP-NENs is often delayed for years and tumors are detected first in an advanced stage. Early identification of a specific hormonal syndrome can significantly impact tumor diagnosis and treatment, moreover the preoperative management of NEN hormonal release avoids potential life threatening hormonal crisis. However, GEP-NEN diagnostic work-up is challenging, it requires a multidisciplinary team and needs particular experience; standardized protocols and clinical experience are essential for a proper endocrine diagnostic work-up. In addition to the biochemical diagnostic, further radiologic and endoscopic imaging modalities are required moreover, somatostatin-receptor based functional imaging, using either Octreotide-scintigraphy or novel PET-based techniques with specific isotopes like Ga⁶⁸-DOTA-octreotate, plays an important role for the detection of the primary tumor as well as for the evaluation of the tumor extent.

Operation for insulinomas in multiple endocrine neoplasia type 1: When pancreatoduodenectomy is appropriate

BACKGROUND

Distal pancreatectomy is the most frequent operation for insulinomas complicating multiple endocrine neoplasia type 1 insulinoma, although there are conditions for which a different operative approach might be preferable. In this article, we report the operative experience of a referral center for multiple endocrine neoplasia type 1 insulinoma.

METHODS

Twelve patients underwent operations between 1992 and 2015: 8 underwent a distal pancreatic resection, and 4 underwent a pancreatoduodenectomy. Enucleation of other macroadenomas present in the remnant pancreas was performed in 9 out of these 12 patients.

RESULTS

Operative complications (2 pancreatic fistulas and 2 cases of pancreatitis) occurred in 4 of the 8 distal pancreatic resections. In 1 patient, reoperation was required to resolve the complications of the first operation. At pathologic analysis, multiple insulinomas were found in 5 patients, lymph-nodal metastasis positive for insulin in 2 patients, multiple nonfunctioning pancreatic tumors in all patients, glucagonoma in 4 patients, and gastrinoma in the duodenum or lymph nodes in 4 patients. All the patients were treated successfully for the hypoglycemic/hyperinsulinemic syndrome with no clinical recurrence at a mean follow-up of 85 months (range 4-242 months). Recurrent nonfunctioning pancreatic tumor macroadenomas in the remnant pancreas occurred in only 1 of the 12 patients, and no progression of the gastrinomas was observed. None of the patients developed diabetes mellitus.

CONCLUSION

Resection of the most severely affected part of the pancreas, whether left or right, associated with enucleation of concomitant macroadenomas in the preserved pancreas is recommended for the treatment of hypoglycemic/hyperinsulinemic syndrome and to prevent malignant progression of nonfunctioning pancreatic tumors in patients with multiple endocrine neoplasia type 1. If the head of the pancreas is the most affected site and the Zollinger-Ellison syndrome is concomitant, then pancreatoduodenectomy should be preferred over distal pancreatectomy.

Pathology, genetics and precursors of human and experimental pancreatic neoplasms: An update

Over the past decade, there have been substantial improvements in our knowledge of pancreatic neoplasms and their precursor lesions. Extensive genetic analyses, recently using high-throughput molecular techniques and next-generation sequencing methodologies, and the development of sophisticated genetically engineered mouse models closely recapitulating human disease, have improved our understanding of the genetic basis of pancreatic neoplasms. These advances are paving the way for refined, molecular-based classifications of pancreatic neoplasms with the potential to better predict prognosis and, possibly, response to therapy. Another major development resides in the identification of subsets of pancreatic exocrine and endocrine neoplasms which occur in the context of hereditary syndromes and whose genetic basis and tumor development have been at least partially defined. However, despite all molecular progress, correct and careful morphological characterization of tissue specimens both in the context of experimental and routine diagnostic pathology represents the basis for any further genetic investigation or clinical decision. This review focuses on the current and new concepts of classification and on the current models of tumor development, both in the field of exocrine and endocrine neoplasms, and underscores the importance of applying standardized terminology to allow adequate data interpretation and promote scientific exchange in the field of pancreas research.

Hyperplasia to neoplasia sequence of duodenal and pancreatic neuroendocrine diseases and pseudohyperplasia of the PP-cells in the pancreas

Hyperplastic changes of the neuroendocrine cell system may have the potential to evolve into neoplastic diseases. This is particularly the case in the setting of genetically determined and hereditary neuroendocrine tumor syndromes such as MEN1. The review discusses the MEN1-associated hyperplasia-neoplasia sequence in the development of gastrinomas in the duodenum and glucagon-producing tumors in the pancreas. It also presents other newly described diseases (e.g., glucagon cell adenomatosis and insulinomatosis) in which the tumors are (or most likely) also preceded by islet cell hyperplasia. Finally, the pseudohyperplasia of PP-rich islets in the pancreatic head is defined as a physiologic condition clearly differing from other hyperplastic-neoplastic neuroendocrine diseases.

Thoracic and duodenopancreatic neuroendocrine tumors in multiple endocrine neoplasia type 1: natural history and function of menin in tumorigenesis

Mutations of the multiple endocrine neoplasia type 1 (MEN1) gene lead to loss of function of its protein product menin. In keeping with its tumor suppressor function in endocrine tissues, the majority of the MEN1-related neuroendocrine tumors (NETs) show loss of heterozygosity (LOH) on chromosome 11q13. In sporadic NETs, MEN1 mutations and LOH are also reported, indicating common pathways in tumor development. Prevalence of thymic NETs (thNETs) and pulmonary carcinoids in MEN1 patients is 2-8%. Pulmonary carcinoids may be underreported and research on natural history is limited, but disease-related mortality is low. thNETs have a high mortality rate. Duodenopancreatic NETs (dpNETs) are multiple, almost universally found at pathology, and associated with precursor lesions. Gastrinomas are usually located in the duodenal submucosa while other dpNETs are predominantly pancreatic. dpNETs are an important determinant of MEN1-related survival, with an estimated 10-year survival of 75%. Survival differs between subtypes and apart from tumor size there are no known prognostic factors. Natural history of nonfunctioning pancreatic NETs needs to be redefined because of increased detection of small tumors. MEN1-related gastrinomas seem to behave similar to their sporadic counterparts, while insulinomas seem to be more aggressive. Investigations into the molecular functions of menin have led to new insights into MEN1-related tumorigenesis. Menin is involved in gene transcription, both as an activator and repressor. It is part of chromatin-modifying protein complexes, indicating involvement of epigenetic pathways in MEN1-related NET development. Future basic and translational research aimed at NETs in large unbiased cohorts will clarify the role of menin in NET tumorigenesis and might lead to new therapeutic options.

Enucleation and limited pancreatic resection provide long-term cure for insulinoma in multiple endocrine neoplasia type 1

AIM

To assess the characteristics and long-term outcome after surgery in patients with multiple endocrine neoplasia type 1 (MEN1)-associated insulinoma.

METHODS

Retrospective analysis of prospectively collected data of MEN1 patients with organic hyperinsulinism at a tertiary referral center.

RESULTS

Thirteen (17%) of 74 patients with MEN1 had organic hyperinsulinism. The median age at diagnosis was 27 (range 9-48) years. In 7 patients insulinoma was the first manifestation of the syndrome. All patients had at least one pancreatic neuroendocrine neoplasm (pNEN) upon imaging, including CT, MRI or endoscopic ultrasonography. Seven patients had solitary lesions upon imaging, 4 patients had one dominant tumor with coexisting multiple small pNENs, and 2 patients had multiple lesions without dominance. Eight patients had limited resections (1 segmental resection, 7 enucleations), 4 subtotal distal pancreatectomies, and 1 patient a partial duodenopancreatectomy. There was no postoperative mortality. Six patients experienced complications, including pancreatic fistula in 5 patients. Pathological examination revealed median three (range 1-14) macro-pNENs sized between 6 and 40 mm, and a total of 14 potentially benign insulinomas were detected in the 13 patients. After median follow-up of 156 months, only 1 patient developed recurrent hyperinsulinism after initial enucleation. Twelve patients developed new pNENs in the pancreatic remnant and 4 patients underwent reoperations (3 for metastatic ZES, 1 for recurrent hyperinsulinism). One of 5 patients with an initial extended pancreatic resection developed insulin-dependent diabetes mellitus.

CONCLUSION

Enucleation and limited resection provide long-term cure for MEN1 insulinoma in patients with solitary or dominant tumors. Subtotal distal pancreatectomy should thus be preserved for patients with multiple pNENs without dominance given the risk of exocrine and endocrine pancreas insufficiency in the mostly young patients.

Hypoglycaemia related to inherited metabolic diseases in adults

In non-diabetic adult patients, hypoglycaemia may be related to drugs, critical illness, cortisol or glucagon insufficiency, non-islet cell tumour, insulinoma, or it may be surreptitious. Nevertheless, some hypoglycaemic episodes remain unexplained, and inborn errors of metabolism (IEM) should be considered, particularly in cases of multisystemic involvement. In children, IEM are considered a differential diagnosis in cases of hypoglycaemia. In adulthood, IEM-related hypoglycaemia can persist in a previously diagnosed childhood disease. Hypoglycaemia may sometimes be a presenting sign of the IEM. Short stature, hepatomegaly, hypogonadism, dysmorphia or muscular symptoms are signs suggestive of IEM-related hypoglycaemia. In both adults and children, hypoglycaemia can be clinically classified according to its timing. Postprandial hypoglycaemia can be an indicator of either endogenous hyperinsulinism linked to non-insulinoma pancreatogenic hypoglycaemia syndrome (NIPHS, unknown incidence in adults) or very rarely, inherited fructose intolerance. Glucokinase-activating mutations (one family) are the only genetic disorder responsible for NIPH in adults that has been clearly identified so far. Exercise-induced hyperinsulinism is linked to an activating mutation of the monocarboxylate transporter 1 (one family). Fasting hypoglycaemia may be caused by IEM that were already diagnosed in childhood and persist into adulthood: glycogen storage disease (GSD) type I, III, 0, VI and IX; glucose transporter 2 deficiency; fatty acid oxidation; ketogenesis disorders; and gluconeogenesis disorders. Fasting hypoglycaemia in adulthood can also be a rare presenting sign of an IEM, especially in GSD type III, fatty acid oxidation [medium-chain acyl-CoA dehydrogenase (MCAD), ketogenesis disorders (3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) lyase deficiency, and gluconeogenesis disorders (fructose-1,6-biphosphatase deficiency)].

[Neuroendocrine neoplasms of the gastrointestinal tract. Classification, clinical presentation and diagnosis]

Neuroendocrine neoplasms of the digestive system represent a rare and heterogeneous group of malignancies with various clinical presentations and prognoses. The WHO classification for the year 2000 was updated in 2010 to take the histopathology and tumor biology of these tumors into account. Together with proliferation-based grading and the recently established staging system using the ENETS TNM classification, it forms the basis for the further diagnostic and therapeutic approach. Clinical presentation depends mainly on the primary site of the tumor and its functionality. Characteristic symptoms are seen only rarely, this being the reason these tumors are usually detected at an advanced stage. Approximately 30% of GEP-NEN are hormonally active and can cause a specific clinical syndrome. In addition to these specific hormones, chromogranin A is considered the most accurate general marker for the biochemical follow-up of these patients. In addition to commonly used radiological and endoscopic imaging modalities, somatostatin receptor-based functional imaging using either octreotide scintigraphy or novel PET-based techniques with specific isotopes such as Ga68-DOTA-octreotate play a crucial role in the detection of the primary tumor as well as in the evaluation of tumor extent and the selection of patients for receptor-based radionuclide therapy.

Classification and pathology of gastroenteropancreatic neuroendocrine neoplasms

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are composed of cells with a neuroendocrine phenotype. The old and the new WHO classifications distinguish between well-differentiated and poorly differentiated neoplasms. All well-differentiated neoplasms, regardless of whether they behave benignly or develop metastases, will be called neuroendocrine tumours (NETs), and graded G1 (Ki67 <2%) or G2 (Ki67 2-20%). All poorly differentiated neoplasms will be termed neuroendocrine carcinomas (NECs) and graded G3 (Ki67 >20%). To stratify the GEP-NETs and GEP-NECs regarding their prognosis, they are now further classified according to TNM-stage systems that were recently proposed by the European Neuroendocrine Tumour Society (ENETS) and the AJCC/UICC. In the light of these criteria the pathology and biology of the various NETs and NECs of the gastrointestinal tract (including the oesophagus) and the pancreas are reviewed.

Neuroendocrine neoplasms of the gastrointestinal tract

BACKGROUND

Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) are complex tumors whose incidence is rising and whose treatment requires precise classification and risk stratification.

METHOD

Selective review of the relevant literature, including recently published guidelines.

RESULTS

GEP-NENs are initially classified by their degree of histological differentiation and their graded cell proliferation (Ki-67 index). In addition, there are GEP-NEN specific TNM staging protocols. The laboratory assessment includes the measurement of general tumor markers (synaptophysin, chromogranin A) as well as specific ones (hormones). The most important imaging technique for diagnosis is octreotide scintigraphy. The surgical treatment of GEP-NEN is based on oncological resection criteria whose aim is to achieve locally radical resection while preserving as much organ function as possible. Metastases, too, may be amenable to resection. The treatment options for unresectable metastases include radiofrequency ablation and chemoembolization, both of which are palliative methods of reducing tumor volume and hormone production. Other chemotherapeutic and nuclear-medical treatments can be applied depending on the extent of metastatic spread, the proliferation index, and the degree of hormone production by the tumor.

CONCLUSION

The accurate diagnosis and appropriate treatment of GEP-NET currently gives most patients with this tumor a good prognosis, as long as it is discovered early. Early GEP-NETs have a favorable prognosis. Further advances in the diagnosis and treatment of this disease may result from structural changes in patient care, including the establishment of NET centers.

Insulin secretion and insulin-producing tumors

Insulinomas are rare neuroendocrine tumors of pancreatic islet cells that retain the ability to produce and secrete insulin. In contrast to normally differentiated β-cells, insulinoma cells continue to secrete insulin and proinsulin at low blood glucose. This deregulated insulin secretion manifests clinically as fasting hypoglycemia. The molecular pathways that characterize normal insulin secretion and β-cell growth are reviewed and contrasted to the biology of insulinomas. The second half of this review summarizes the clinical approach to the disorder. The diagnosis of insulinoma is established by demonstrating inappropriately high insulin levels with coincident hypoglycemia at the time of a supervised fast. Localization of insulinomas is challenging owing to their small size but should be attempted to maximize the chance for successful surgical resection and avoid risks associated with reoperation. In the majority of cases, successful surgical resection leads to lifelong cure.

Insulinoma: pathophysiology, localization and management

Insulinoma is a rare neuroendocrine tumor that causes oversecretion of insulin and, as a result, patients present with symptoms of hypoglycemia. Fortunately, insulinomas are usually benign and solitary, and surgical cure rates are highly favorable. Most of these tumors occur sporadically, but they can also be associated with multiple endocrine neoplasia type-1 syndrome. The diagnosis is confirmed by a supervised fast, and early detection is important. Several preoperative and intraoperative techniques with various success rates have been employed in order to localize the lesion. When technically feasible, tumor enucleation is the procedure of choice; however, a more formal resection may be necessary for certain tumors. In the age of laparoscopy, the role of laparoscopic surgery in the management of insulinomas is continuing to attract attention. This review will discuss the historical background, pathogenesis, diagnosis, localization and management of insulinomas.

[Hypoglycemia and insulinoma]

Insulinomas are rare causes of hypoglycemia. After having ruled out non insulinomatous causes of hypoglycemia in a patient in whom Whipple's triad is documented, hyperinsulinism must be demonstrated biochemically, either during a spontaneous hypoglycemic episode or, more often, during a supervised fast which may be prolonged up to 72 h. A mixed-meal test may also help to diagnose the very rare cases of postprandial hypoglycemia related to non insulinoma pancreatogenic hypoglycemic syndrome (NIPHS) or to some rare insulinomas. Only when diagnosis of hypoglycemic hyperinsulinism is made, the tumor localization process may be initiated. This may be difficult due to the small size of insulinomas (generally < 1 cm). Multimodal approach is necessary. The association of endoscopic ultrasound and CT-scan or MRI seems optimal. Octreoscan will be also performed. First results with a very new technique, the GLP-1 receptor imaging, are promising for localizing very small tumors. This localization aims to allow a sparing surgery; enucleation of benign tumors, if possible, allows a pancreatic tissue preservation in patients with quite normal survival.