Congenital Hyperinsulinism

Case Report: The importance of genetic counseling for families with hyperinsulinism

Congenital hyperinsulinism (HI) is the most common cause of persistent hypoglycemia in infancy. Genotype-phenotype correlations directly inform medical care for patients. Understanding the genetic etiology also allows accurate genetic counseling to be provided, illustrated by two families following a diagnosis of HI. A newborn had hypoglycemia at birth and was diagnosed with focal HI due to a paternally inherited recessive ABCC8 variant. Years later the paternal half-sibling was diagnosed with HI. Testing revealed compound heterozygous ABCC8 variants, consistent with diffuse disease. Following testing, the father's partner(s) should have been offered carrier testing. However, the parents were unaware that future children could be at increased risk of HI. The second family's son was diagnosed with HI in infancy and genetic testing identified a heterozygous recessive ABCC8 variant. Parental testing revealed both parents carried this variant. Focal HI was subsequently confirmed. This family's 1/4 chance to have a child with diffuse HI was significantly higher than the 1/540 chance their child could have focal HI. Understanding the etiology of a patient's HI not only allows for appropriate medical management but has important reproductive implications for the family. Genetic counseling is an important component of the multidisciplinary care received by every family with HI.

International Guidelines for the Diagnosis and Management of Hyperinsulinism

BACKGROUND

Hyperinsulinism (HI) due to dysregulation of pancreatic beta-cell insulin secretion is the most common and most severe cause of persistent hypoglycemia in infants and children. In the 65 years since HI in children was first described, there has been a dramatic advancement in the diagnostic tools available, including new genetic techniques and novel radiologic imaging for focal HI; however, there have been almost no new therapeutic modalities since the development of diazoxide.

SUMMARY

Recent advances in neonatal research and genetics have improved our understanding of the pathophysiology of both transient and persistent forms of neonatal hyperinsulinism. Rapid turnaround of genetic test results combined with advanced radiologic imaging can permit identification and localization of surgically-curable focal lesions in a large proportion of children with congenital forms of HI, but are only available in certain centers in "developed" countries. Diazoxide, the only drug currently approved for treating HI, was recently designated as an "essential medicine" by the World Health Organization but has been approved in only 16% of Latin American countries and remains unavailable in many under-developed areas of the world. Novel treatments for HI are emerging, but they await completion of safety and efficacy trials before being considered for clinical use.

KEY MESSAGES

This international consensus statement on diagnosis and management of HI was developed in order to assist specialists, general pediatricians, and neonatologists in early recognition and treatment of HI with the ultimate aim of reducing the prevalence of brain injury caused by hypoglycemia. A previous statement on diagnosis and management of HI in Japan was published in 2017. The current document provides an updated guideline for management of infants and children with HI and includes potential accommodations for less-developed regions of the world where resources may be limited.

Intraoperative ultrasound imaging in the surgical treatment of congenital hyperinsulinism: prospective, blinded study

Background

In congenital hyperinsulinism (CHI), preoperative prediction of the histological subtype (focal, diffuse, or atypical) relies on genetics and 6-[¹⁸F]fluoro-l-3,4-dihydroxyphenylalanine (¹⁸F-DOPA) PET–CT. The scan also guides the localization of a potential focal lesion along with perioperative frozen sections. Intraoperative decision-making is still challenging. This study aimed to describe the characteristics and potential clinical impact of intraoperative ultrasound imaging (IOUS) during CHI surgery.

Methods

This was a prospective, observational study undertaken at an expert centre over a 2-year interval. IOUS was performed blinded to preoperative diagnostic test results (genetics and ¹⁸F-DOPA PET–CT), followed by unblinding and continued IOUS during pancreatic resection. Characteristics and clinical impact were assessed using predefined criteria.

Results

Eighteen consecutive, surgically treated patients with CHI, with a median age of 5.5 months, were included (focal 12, diffuse 3, atypical 3). Focal lesions presented as predominantly hypoechoic, oval lesions with demarcated or blurred margins. Patients with diffuse and atypical disease had varying echogenicity featuring stranding and non-shadowing hyperechoic foci in three of six, whereas these characteristics were absent from those with focal lesions. The blinded IOUS-based subclassification was correct in 17 of 18 patients; one diffuse lesion was misclassified as focal. IOUS had an impact on the surgical approach in most patients with focal lesions (9 of 12), and in those with diffuse (2 of 3) and atypical (2 of 3) disease when the resection site was close to the bile or pancreatic duct.

Conclusion

Uniform IOUS characteristics made all focal lesions identifiable. IOUS had a clinical impact in 13 of 18 patients by being a useful real-time supplementary modality in terms of localizing focal lesions, reducing the need for frozen sections, and preserving healthy tissue and delicate structures.

Suspected congenital hyperinsulinism in a Shiba Inu dog

A 3‐month‐old male intact Shiba Inu dog was evaluated for a seizure disorder initially deemed idiopathic in origin. Seizure frequency remained unchanged despite therapeutic serum phenobarbital concentration and use of levetiracetam. The dog was documented to be markedly hypoglycemic during a seizure episode on reevaluation at 6 months of age. Serum insulin concentrations during hypoglycemia were 41 U/μL (reference range, 10‐29 U/μL). The dog was transitioned to 4 times per day feeding, diazoxide was started at 3.5 mg/kg PO q8h, and antiepileptic drugs were discontinued. No clinically relevant abnormalities were identified on bicavitary arterial and venous phase contrast computed tomographic imaging. The dog remained seizure‐free and clinically normal at 3 years of age while receiving 5.5 mg/kg diazoxide PO q12h and twice daily feeding. Seizures later occurred approximately twice per year and after exertion, with or without vomiting of a diazoxide dose. Blood glucose curves and interstitial glucose monitoring were used to titrate diazoxide dose and dosing interval. Congenital hyperinsulinism is well recognized in people but has not been reported in veterinary medicine.

Efficacy and safety of octreotide treatment for diazoxide-unresponsive congenital hyperinsulinism in China

IMPORTANCE

Octreotide is an off-label medicine for congenital hyperinsulinism (CHI), but is currently widely used for treatment of patients with CHI. Thus far, variable efficacy and adverse effects have been reported for octreotide.

OBJECTIVE

The present study evaluated the efficacy and safety of a subcutaneous octreotide injection for treatment of diazoxide-unresponsive CHI in China.

METHODS

This study was a retrospective review of children with diazoxide-unresponsive CHI who were treated with a subcutaneous octreotide injection. The efficacy and side effects of the treatment were assessed.

RESULTS

Twenty-five Chinese children (15 boys) were involved in the study. Their median age at diagnosis was 8 weeks (range, 1-24 weeks) and median age at the final follow-up was 1.8 years (range, 0.3-3.3 years). Octreotide therapy effectively increased blood glucose levels in all patients. The intravenous glucose infusion rate was reduced in all patients. Twenty-one patients gradually discontinued the intravenous glucose infusion while receiving octreotide combined with frequent carbohydrate/glucose-rich feeding. Among patients with a monoallelic ATP-sensitive potassium (KATP) channel mutation, 50.0% showed gradual remission during follow up, indicating that the octreotide treatment may be a feasible alternative to surgery, especially for patients with monoallelic KATP-channel mutations. Transient elevation of liver enzymes occurred in 20.0% of patients, while asymptomatic gallbladder pathology occurred in one patient. The growth rates of these patients were normal (height standard deviation score was 0.3 ± 1.5 at the final follow-up).

INTERPRETATION

Octreotide was a well-tolerated, effective therapy for most children with diazoxide-unresponsive CHI.

Unravelling the genetic causes of mosaic islet morphology in congenital hyperinsulinism

Congenital hyperinsulinism (CHI) causes dysregulated insulin secretion which can lead to life‐threatening hypoglycaemia if not effectively managed. CHI can be sub‐classified into three distinct groups: diffuse, focal and mosaic pancreatic disease. Whilst the underlying causes of diffuse and focal disease have been widely characterised, the genetic basis of mosaic pancreatic disease is not known. To gain new insights into the underlying disease processes of mosaic‐CHI we studied the islet tissue histopathology derived from limited surgical resection from the tail of the pancreas in a patient with CHI. The underlying genetic aetiology was investigated using a combination of high depth next‐generation sequencing, microsatellite analysis and p57kip2 immunostaining. Histopathology of the pancreatic tissue confirmed the presence of a defined area associated with marked islet hypertrophy and a cytoarchitecture distinct from focal CHI but compatible with mosaic CHI localised to a discrete region within the pancreas. Analysis of DNA extracted from the lesion identified a de novo mosaic ABCC8 mutation and mosaic paternal uniparental disomy which were not present in leukocyte DNA or the surrounding unaffected pancreatic tissue. This study provides the first description of two independent disease‐causing somatic genetic events occurring within the pancreas of an individual with localised mosaic CHI. Our findings increase knowledge of the genetic causes of islet disease and provide further insights into the underlying developmental changes associated with β‐cell expansion in CHI.

Clinical practice guidelines for congenital hyperinsulinism

Congenital hyperinsulinism is a rare condition, and following recent advances in diagnosis and treatment, it was considered necessary to formulate evidence-based clinical practice guidelines reflecting the most recent progress, to guide the practice of neonatologists, pediatric endocrinologists, general pediatricians, and pediatric surgeons. These guidelines cover a range of aspects, including general features of congenital hyperinsulinism, diagnostic criteria and tools for diagnosis, first- and second-line medical treatment, criteria for and details of surgical treatment, and future perspectives. These guidelines were generated as a collaborative effort between The Japanese Society for Pediatric Endocrinology and The Japanese Society of Pediatric Surgeons, and followed the official procedures of guideline generation to identify important clinical questions, perform a systematic literature review (April 2016), assess the evidence level of each paper, formulate the guidelines, and obtain public comments.

Single incision laparoscopic 90 % pancreatectomy for the treatment of persistent hyperinsulinemic hypoglycemia of infancy

Single incision laparoscopic surgery as a surgical approach in treatment of pancreatic disease has recently been reported in adults. However, its application in persistent hyperinsulinemic hypoglycemia of infancy (PHHI) in children is limited. In this article, we report single incision laparoscopic 90 % pancreatectomy for the treatment of persistent hyperinsulinemic hypoglycemia of infancy. Between July 2011 and February 2015, the single incision laparoscopic 90 % pancreatectomy was performed in three children with PHHI. All patients underwent (18)F-FDOPA PET/CT before the surgeries. The scans showed diffuse physiologic (18)F-FDOPA activity in entire pancreas. All patients were followed up. The levels of blood sugar and insulin were recorded postoperatively. The time required for surgery was 120-230 min, and blood loss was minimal. The hospital stay was 6 days. The duration of postoperative abdominal drainage was 4-5 days. The levels of fasting blood glucose after surgery were higher than those before surgery (4.38-8.9 vs. 0.54-1.8 mmol/L). The levels of fasting insulin after surgery were lower than those before surgery (2.4-5.5 vs. 14-33.3 uU/ml). The duration of follow-up was 4-46 months. During follow-up, the levels of blood glucose and insulin were normal in three patients. There was no recurrence of hypoglycemia after operation in all patients. Single incision laparoscopic 90 % pancreatectomy for children with PHHI is feasible and safe in well-selected cases in the experienced centers.

Perspective on the Genetics and Diagnosis of Congenital Hyperinsulinism Disorders

CONTEXT

Congenital hyperinsulinism (HI) is the most common cause of hypoglycemia in children. The risk of permanent brain injury in infants with HI continues to be as high as 25-50% due to delays in diagnosis and inadequate treatment. Congenital HI has been described since the birth of the JCEM under various terms, including "idiopathic hypoglycemia of infancy," "leucine-sensitive hypoglycemia," or "nesidioblastosis."

EVIDENCE ACQUISITION

In the past 20 years, it has become apparent that HI is caused by genetic defects in the pathways that regulate pancreatic β-cell insulin secretion.

EVIDENCE SYNTHESIS

There are now 11 genes associated with monogenic forms of HI (ABCC8, KCNJ11, GLUD1, GCK, HADH1, UCP2, MCT1, HNF4A, HNF1A, HK1, PGM1), as well as several syndromic genetic forms of HI (eg, Beckwith-Wiedemann, Kabuki, and Turner syndromes). HI is also the cause of hypoglycemia in transitional neonatal hypoglycemia and in persistent hypoglycemia in various groups of high-risk neonates (such as birth asphyxia, small for gestational age birthweight, infant of diabetic mother). Management of HI is one of the most difficult problems faced by pediatric endocrinologists and frequently requires difficult choices, such as near-total pancreatectomy and/or highly intensive care with continuous tube feedings. For 50 years, diazoxide, a KATP channel agonist, has been the primary drug for infants with HI; however, it is ineffective in most cases with mutations of ABCC8 or KCNJ11, which constitute the majority of infants with monogenic HI.

CONCLUSIONS

Genetic mutation testing has become standard of care for infants with HI and has proven to be useful not only in projecting prognosis and family counseling, but also in diagnosing infants with surgically curable focal HI lesions. (18)F-fluoro-L-dihydroxyphenylalanine ((18)F-DOPA) PET scans have been found to be highly accurate for localizing such focal lesions preoperatively. New drugs under investigation provide hope for improving the outcomes of children with HI.

Minimally invasive surgical interventions in the treatment of primary persistent hyperinsulinemic hypoglycemia of infancy

Hyperinsulinemia, diagnosed by laboratory tests, should be diagnosed and treated as soon as possible to prevent fatal complications such as neurological damage. Patients who are resistant to medical therapy should be treated surgically. Minimally invasive surgery, a newly developed approach, is a good choice among surgical procedures to avoid unnecessary extensive pancreatectomy. Here, a 12-year-old boy is presented with diagnosis of hyperinsulinemic hypoglycemia who had recurrent attacks of hypoglycemia and seizures from infancy. Because of his unresponsiveness to medical therapy and his family's preference, he underwent laparoscopic pancreatectomy to reduce morbidity and hospital stay. Two years postsurgical follow-up revealed a normo-glycemic state.

Altered Phenotype of β-Cells and Other Pancreatic Cell Lineages in Patients With Diffuse Congenital Hyperinsulinism in Infancy Caused by Mutations in the ATP-Sensitive K-Channel

Diffuse congenital hyperinsulinism in infancy (CHI-D) arises from mutations inactivating the KATP channel; however, the phenotype is difficult to explain from electrophysiology alone. Here we studied wider abnormalities in the β-cell and other pancreatic lineages. Islets were disorganized in CHI-D compared with controls. PAX4 and ARX expression was decreased. A tendency toward increased NKX2.2 expression was consistent with its detection in two-thirds of CHI-D δ-cell nuclei, similar to the fetal pancreas, and implied immature δ-cell function. CHI-D δ-cells also comprised 10% of cells displaying nucleomegaly. In CHI-D, increased proliferation was most elevated in duct (5- to 11-fold) and acinar (7- to 47-fold) lineages. Increased β-cell proliferation observed in some cases was offset by an increase in apoptosis; this is in keeping with no difference in INSULIN expression or surface area stained for insulin between CHI-D and control pancreas. However, nuclear localization of CDK6 and P27 was markedly enhanced in CHI-D β-cells compared with cytoplasmic localization in control cells. These combined data support normal β-cell mass in CHI-D, but with G1/S molecules positioned in favor of cell cycle progression. New molecular abnormalities in δ-cells and marked proliferative increases in other pancreatic lineages indicate CHI-D is not solely a β-cell disorder.

Congenital hyperinsulinism: global and Japanese perspectives

Over the past 20 years, there has been remarkable progress in the diagnosis and treatment of congenital hyperinsulinism (CHI). These advances have been supported by the understanding of the molecular mechanism and the development of diagnostic modalities to identify the focal form of ATP-sensitive potassium channel CHI. Many patients with diazoxide-unresponsive focal CHI have been cured by partial pancreatectomy without developing postsurgical diabetes mellitus. Important novel findings on the genetic basis of the other forms of CHI have also been obtained, and several novel medical treatments have been explored. However, the management of patients with CHI is still far from ideal. First, state-of-the-art treatment is not widely available worldwide. Second, it appears that the management strategy needs to be adjusted according to the patient's ethnic group. Third, optimal management of patients with the diazoxide-unresponsive, diffuse form of CHI is still insufficient and requires further improvement. In this review, we describe the current landscape of this disorder, discuss the racial disparity of CHI using Japanese patients as an example, and briefly note unanswered questions and unmet needs that should be addressed in the near future.

Congenital hyperinsulinism: current status and future perspectives

The diagnosis and treatment of congenital hyperinsulinism (CHI) have made a remarkable progress over the past 20 years and, currently, it is relatively rare to see patients who are left with severe psychomotor delay. The improvement was made possible by the recent developments in the understanding of the molecular and pathological basis of CHI. Known etiologies include inactivating mutations of the KATP channel genes (ABCC8 and KCNJ11) and HNF4A, HNF1A, HADH, and UCP2 or activating mutations of GLUD1, GCK, and SLC16A1. The understanding of the focal form of KATP channel CHI and its detection by (18)F-fluoro-L-DOPA positron emission tomography have revolutionized the management of CHI, and many patients can be cured without postoperative diabetes mellitus. The incidence of the focal form appears to be higher in Asian countries; therefore, the establishment of treatment systems is even more important in this population. In addition to diazoxide or long-term subcutaneous infusion of octreotide or glucagon, long-acting octreotide or lanreotide have also been used successfully until spontaneous remission. Because of these medications, near-total pancreatectomy is less often performed even for the diazoxide-unresponsive diffuse form of CHI. Other promising medications include pasireotide, small-molecule correctors such as sulfonylurea or carbamazepine, GLP1 receptor antagonists, or mammalian target of rapamycin inhibitors. Unsolved questions in this field include the identification of the remaining genes responsible for CHI, the mechanisms leading to transient CHI, and the mechanisms responsible for the spontaneous remission of CHI. This article reviews recent developments and hypothesis regarding these questions.

Hyperinsulinism presenting in childhood and treatment by conservative pancreatectomy

OBJECTIVE

To describe the uncommon presentation of hyperinsulinism in an 8-year-old boy.

METHODS

We describe the patient's clinical findings, results from biochemical and imaging studies, surgical approach, and outcome. The discussion encompasses a review of literature that provided the basis for the diagnostic and surgical approach applied to this patient's case.

RESULTS

An obese 8.5-year-old boy initially presented with hypoglycemic seizures after initiation of dietary changes to treat obesity. Biochemical analysis indicated hyperinsulinism. Endoscopic ultrasonography showed no pancreatic lesions suggestive of insulinoma. Genetic studies identified no known mutations in the ABCC8, KCNJ11, GCK, or GLUD1 genes. Selective arterial calcium stimulation and hepatic venous sampling did not document a focal source for hyperinsulinism in the pancreas, and positron emission tomography with 18-fluoro-L-3,4-dihydroxyphenylalanine showed diffusely increased uptake in the pancreas. The patient ultimately required partial pancreatectomy because of continued hypoglycemia while taking diazoxide and octreotide. Intraoperative glucose monitoring directed the extent of surgical resection. A 45% pancreatectomy was performed, which resolved the hypoglycemia but led to impaired glucose tolerance after surgery.

CONCLUSION

The unusual presentation of hyperinsulinism in childhood required a personalized approach to diagnosis and surgical management using intraoperative glucose monitoring that resulted in a conservative pancreatectomy.

Morphologic analysis of focal and diffuse forms of congenital hyperinsulinism

Congenital hyperinsulinism is clinically characterized by an inappropriate insulin secretion resulting in recurrent severe hypoglycemia. Nesidioblastosis, the proliferation of islet cells budding off from ducts, has been considered for years as the histologic lesion responsible for the syndrome. In our morphologic studies, we demonstrate that nesidioblastosis is not specific of the disease, which is actually not a single entity. Indeed, we recognize the existence of 2 different forms-a diffuse form and a focal form-and demonstrate that they can be differentiated by morphologic criteria, even on frozen sections during surgery. This histologic distinction directs the therapeutic approach because the patients experiencing the focal form of the syndrome can be completely cured by a very limited pancreatectomy. Molecular findings confirmed the reliability of this histologic distinction, showing a specific background for each form.

A specialized team approach to diagnosis and medical versus surgical treatment of infants with congenital hyperinsulinism

Hyperinsulinism (HI) is the most common cause of transient and permanent forms of hypoglycemia in infancy. Establishing the correct diagnosis and initiating appropriate therapy without delay is of utmost importance. Once the diagnosis is made and if medical therapy with diazoxide fails, one should assume that the infant has a K(ATP) channel defect and may require surgery. In this case, the infant should be referred to a center that specializes in HI with 18-fluoro L-3,4-dihydroxyphenylalanine positron emission tomography scan. This report describes a center specializing in HI with a team of experts consisting of endocrinologists, nurse practitioners, geneticists, radiologists, pathologists, and a surgeon. It describes the center's paradigm for managing severe HI on the basis of more than 250 cases of HI in the past 10 years, including the diagnosis of HI, medical options, genetics of HI, imaging in HI, the surgical approach to HI, and outcomes.

Congenital hyperinsulinism in Brazilian neonates: a study of histology, KATP channel genes, and proliferation of β cells

Congenital hyperinsulinism (CHI) is a rare pancreatic β-cell disease of neonates, characterized by inappropriate insulin secretion with severe persistent hypoglycemia, with regard to which many questions remain to be answered, despite the important acquisition of its molecular mechanisms in the last decade. The aim of this study was to examine pancreatic histology, β-cell proliferation (immunohistochemistry with double staining for Ki-67/insulin), and β-cell adenosine triphosphate-sensitive potassium channels genes from 11 Brazilian patients with severe medically unresponsive CHI who underwent pancreatectomy. Pancreatic histology and β-cell proliferation in CHI patients were compared to pancreatic samples from 19 age-matched controls. Ten cases were classified as diffuse form (D-CHI) and 1 as focal form (F-CHI). β-cell nucleomegaly and abundant cytoplasm were absent in controls and were observed only in D-CHI patients. The Ki-67 labeling index (Ki-67-LI) was used to differentiate the adenomatous areas of the F-CHI case (10.15%) from the "loose cluster of islets" found in 2 D-CHI samples (2.29% and 2.43%) and 1 control (1.54%) sample. The Ki-67-LI was higher in the F-CHI adenomatous areas, but D-CHI patients also had significantly greater Ki-67-LI (mean value  =  2.41%) than age-matched controls (mean value  =  1.87%) (P  =  0.009). In this 1st genetic study of CHI patients in Brazil, no mutations or new polymorphisms were found in the 33-37 exons of the ABCC8 gene (SUR1) or in the entire exon of the KCNJ11 gene (Kir 6.2) in 4 of 4 patients evaluated. On the other hand, enhanced β-cell proliferation seems to be a constant feature in CHI patients, both in diffuse and focal forms.

Mitogenic cardiomyopathy: a lethal neonatal familial dilated cardiomyopathy characterized by myocyte hyperplasia and proliferation

Pediatric cardiomyopathies are a heterogenous group of conditions of which dilated cardiomyopathies are the most common clinicomorphologic subtype. However, the etiology and pathogenesis of many cases of dilated cardiomyopathies remain unknown. We describe a series of 5 cases of a rare but clinically and histologically distinctive dilated cardiomyopathy that was uniformly lethal in early infancy. The 5 cases include 2 pairs of siblings. There was parental consanguinity in 1 of the 2 pairs of siblings. Death occurred in early infancy (range, 22-67 days; mean, 42 days) after a short history of general lethargy, decreased feeding, respiratory distress, or cyanosis. There was no specific birth or early neonatal problems. Autopsy revealed congestive cardiac failure and enlarged, dilated hearts with ventricular dilatation more pronounced than atrial dilatation, and endocardial fibroelastosis. Histology showed prominent hypertrophic nuclear changes of cardiac myofibers and markedly increased myocyte mitotic activity including occasional atypical mitoses. Immunohistochemical staining for Mib1 showed a markedly increased proliferative index of 10% to 20%. Ancillary investigations, including molecular studies, did not reveal a primary cause for the cardiomyopathies. This distinctive dilated cardiomyopathy characterized by unusual histologic features of myocyte nuclear hypertrophy and marked mitotic activity is lethal in early infancy. Its occurrence in 2 pairs of siblings suggests familial inheritance. Although the underlying molecular pathogenesis remains to be elucidated, it is important to recognize this distinctive entity for purposes of genetic counseling.

Fluorine-18 DOPA-PET and PET/CT Imaging in Congenital Hyperinsulinism

Congenital hyperinsulinism is the principle cause of hypoglycemia during infancy but successful treatment is difficult and persistent hypoglycemia carries the risk of neurologic damage. Focal and diffuse abnormalities are the common forms of hyperinsulinism. Identification and localization of focal hyperinsulinism can be cured by partial pancreatectomy. It has been shown that affected pancreatic areas utilize LDOPA in a higher rate than normal pancreatic tissue and, thus, labeling L-DOPA with fluorine-18 (FDOPA) allows functional mapping of hyperinsulinism using PET. This article presents a fundamental overview of the genetics background, pathology, management, and the role of FDOPA-PET imaging in hyperinsulinism.

Evaluation of [18F]fluoro-L-DOPA positron emission tomography-computed tomography for surgery in focal congenital hyperinsulinism

CONTEXT

In congenital hyperinsulinism (CHI), the identification and precise localization of a focal lesion is essential for successful surgery.

OBJECTIVE

Our objective was to evaluate the predictive value and accuracy of integrated [18F]fluoro-L-DOPA ([18F]FDOPA) positron emission tomography (PET)-computed tomography (CT) for the surgical therapy of CHI.

DESIGN

This was an observational study.

SETTING

The study was performed in the Department of Pediatric Surgery at a university hospital.

PATIENTS

From February 2005 to September 2007, 10 children with the clinical signs of CHI and an increased radiotracer uptake in a circumscribed area of the pancreas in the [18F]FDOPA PET-CT were evaluated.

INTERVENTIONS

Guided by the [18F]FDOPA PET-CT report, all children underwent partial pancreatic resection, in two cases twice.

MAIN OUTCOME MEASURES

Correlation of the anatomical findings at surgery with the report of the [18F]FDOPA PET-CT, and the results of surgery and clinical outcome were determined.

RESULTS

In nine children the intraoperative situation corresponded exactly to the description of the [18F]FDOPA PET-CT. A limited resection of the pancreas was curative in eight cases at the first surgery, in one case at the second intervention. We observed no diabetes mellitus or exocrine insufficiency in the follow up so far. In one child, hypoglycemia persisted even after two partial resections of the pancreatic head. Histological analysis finally revealed an atypical intermediate form of CHI.

CONCLUSIONS

The integrated [18F]FDOPA PET-CT is accurate to localize the lesion in focal CHI and is a valuable tool to guide the surgeon in limited pancreatic resection.

Hyperinsulinism in Infancy and Childhood: When an Insulin Level Is Not Always Enough

Background: Hypoglycemia in infants and children can lead to seizures, developmental delay, and permanent brain damage. Hyperinsulinism (HI) is the most common cause of both transient and permanent disorders of hypoglycemia. HI is characterized by dysregulated insulin secretion, which results in persistent mild to severe hypoglycemia. The various forms of HI represent a group of clinically, genetically, and morphologically heterogeneous disorders.

Content: Congenital hyperinsulinism is associated with mutations of SUR-1 and Kir6.2, glucokinase, glutamate dehydrogenase, short-chain 3-hydroxyacyl-CoA dehydrogenase, and ectopic expression on β-cell plasma membrane of SLC16A1. Hyperinsulinism can be associated with perinatal stress such as birth asphyxia, maternal toxemia, prematurity, or intrauterine growth retardation, resulting in prolonged neonatal hypoglycemia. Mimickers of hyperinsulinism include neonatal panhypopituitarism, drug-induced hypoglycemia, insulinoma, antiinsulin and insulin-receptor stimulating antibodies, Beckwith-Wiedemann Syndrome, and congenital disorders of glycosylation. Laboratory testing for hyperinsulinism may include quantification of blood glucose, plasma insulin, plasma β-hydroxybutyrate, plasma fatty acids, plasma ammonia, plasma acylcarnitine profile, and urine organic acids. Genetic testing is available through commercial laboratories for genes known to be associated with hyperinsulinism. Acute insulin response (AIR) tests are useful in phenotypic characterization. Imaging and histologic tools are also available for diagnosing and classifying hyperinsulinism. The goal of treatment in infants with hyperinsulinism is to prevent brain damage from hypoglycemia by maintaining plasma glucose levels above 700 mg/L (70 mg/dL) through pharmacologic or surgical therapy.

Summary: The management of hyperinsulinism requires a multidisciplinary approach that includes pediatric endocrinologists, radiologists, surgeons, and pathologists who are trained in diagnosing, identifying, and treating hyperinsulinism.

The laparoscopic approach toward hyperinsulinism in children

Hyperinsulinemic hypoglycemia (HH) in children requiring surgery is rare. Early HH can be the result of focal or diffuse pancreatic pathology. A number of genetic abnormalities in early HH have been identified, but in the majority of patients no abnormality is found. The sporadic focal and diffuse forms as well the autosomal recessive form are particularly therapy-resistant and demand for early surgery. Preoperative discrimination between focal and diffuse disease in early HH is difficult. 18 F DOPA PET in combination with CT is promising as is laparoscopic exploration of the pancreas. Frozen section biopsy analysis has not been uniformly beneficial. If macroscopically no focal lesion is found, limited laparoscopic distal pancreatectomy provides tissue for definitive pathologic examination. Subsequent near total laparoscopic spleen-saving pancreatectomy surgery is not particularly difficult. Later HH may occur in the context of the MEN-1 syndrome and is then multifocal in nature. In MEN-1 patients, a distal spleen-saving pancreatectomy with enucleation of lesions in the head seems justified. Insulin-producing lesions in non-MEN-1 patients should be enucleated. There should always be a suspicion of malignancy. Also, in older children, surgery for hyperinsulinism should be performed laparoscopically.

Monogenic disorders of the pancreatic β-cell: personalizing treatment for rare forms of diabetes and hypoglycemia

Over the past 10–20 years, our understanding of the genetic etiology of monogenic disorders of the pancreatic β-cell has greatly improved. This has enabled clinicians to provide patients with more accurate information regarding prognosis and inheritance and has influenced treatment. Maturity-onset diabetes of the young and neonatal diabetes are two such examples. Patients with maturity-onset diabetes of the young due to glucokinase mutations can usually be managed by diet alone, while those affected by HNF-1α and HNF-4α mutations respond well to low doses of sulfonylureas. The identification of mutations in the ATP-dependent potassium channel genes KCNJ11 and ABCC8 as the most common cause of permanent neonatal diabetes has improved treatment regimes for affected children. In addition to enabling patients to stop insulin injections, their glycemic control has also improved. These advances show the importance of unravelling the genetics of a disease to achieve the best individualized treatment for the patients affected.

Congenital hyperinsulinism - a review of the disorder and a discussion of the anesthesia management

Congenital hyperinsulinism (CHI) is the most common cause of persistent hypoglycemia in infants and children. In most affected infants, CHI is caused by a specific genetic defect that results in the altered expression of pancreatic beta cells causing unregulated oversecretion of insulin. Infants with CHI may have either focal or diffuse abnormalities of the pancreatic beta-cells. Both forms of CHI manifest as hypoglycemia, usually in the early newborn period. Focal disease can be treated effectively with surgical resection of the affected area, resulting in a total cure or rendering the patient amenable to medical management. Most children with diffuse disease are unresponsive to medical therapy, and require near-total pancreatectomy. At The Children's Hospital of Philadelphia, we have developed a multidisciplinary program for diagnosis and treatment of CHI. Anesthesiologists have played an integral role in the perioperative care of these infants, which includes diagnostic procedures, partial or near-total pancreatectomy, and postoperative pain management. In this review, we describe the clinical features, diagnostic methods and anesthetic concerns in children with CHI.

Neonatal hyperinsulinism: clinicopathologic correlation

Neonatal hyperinsulinism is a life-threatening disease that, when treated by total pancreatectomy, leads to diabetes and pancreatic insufficiency. A more conservative approach is now possible since the separation of the disease into a nonrecurring focal form, which is cured by partial surgery, and a diffuse form, which necessitates total pancreas removal only in cases of medical treatment failure. The pathogenesis of the disease is now divided into K-channel disease (hyperinsulinemic hypoglycemia, familial [HHF] 1 and 2), which can mandate surgery, and other metabolic causes, HHF 3 to 6, which are treated medically in most patients. The diffuse form is inherited as a recessive gene on chromosome 11, whereas most cases of the focal form are caused by a sulfonylurea receptor 1 defect inherited from the father, which is associated with a loss of heterozygosity on the corresponding part of the mother's chromosome 11. The rare bifocal forms result from a maternal loss of heterozygosity specific to each focus. Paternal disomy of chromosome 11 is a rare cause of a condition similar to Beckwith-Wiedemann syndrome. A preoperative PET scan with fluorodihydroxyphenylalanine and perioperative frozen-section confirmation are the types of studies done before surgery when needed. Adult variants of the disease are less well defined at the present time.

Mechanisms of Disease: advances in diagnosis and treatment of hyperinsulinism in neonates

Hyperinsulinism is the single most common mechanism of hypoglycemia in neonates. Dysregulated insulin secretion is responsible for the transient and prolonged forms of neonatal hypoglycemia, and congenital genetic disorders of insulin regulation represent the most common of the permanent disorders of hypoglycemia. Mutations in at least five genes have been associated with congenital hyperinsulinism: they encode glucokinase, glutamate dehydrogenase, the mitochondrial enzyme short-chain 3-hydroxyacyl-CoA dehydrogenase, and the two components (sulfonylurea receptor 1 and potassium inward rectifying channel, subfamily J, member 11) of the ATP-sensitive potassium channels (K(ATP) channels). K(ATP) hyperinsulinism is the most common and severe form of congenital hyperinsulinism. Infants suffering from K(ATP) hyperinsulinism present shortly after birth with severe and persistent hypoglycemia, and the majority are unresponsive to medical therapy, thus requiring pancreatectomy. In up to 40-60% of the children with K(ATP) hyperinsulinism, the defect is limited to a focal lesion in the pancreas. In these children, local resection results in cure with avoidance of the complications inherent to a near-total pancreatectomy. Hyperinsulinism can also be part of other disorders such as Beckwith-Wiedemann syndrome and congenital disorders of glycosylation. The diagnosis and management of children with congenital hyperinsulinism requires a multidisciplinary approach to achieve the goal of therapy: prevention of permanent brain damage due to recurrent hypoglycemia.

Genotype-phenotype associations in patients with severe hyperinsulinism of infancy

In hyperinsulinism of infancy (HI), unregulated insulin secretion causes hypoglycemia. Pancreatectomy may be required in severe cases, most of which result from a defect in the beta-cell KATP channel, encoded by ABCC8 and KCNJ11. Pancreatic histology may be classified as diffuse or focal disease (the latter associated with single paternal ABCC8 mutations), indicated by the presence of islet cell nuclear enlargement in areas of diffuse abnormality. We investigated genotype-phenotype associations in a heterogeneous Australian cohort. ABCC8 and KCNJ11 genes were sequenced and case histology was reviewed in 21 infants who had pancreatectomy. Ninety-eight control DNA samples were tested by single nucleotide polymorphism analysis. Eighteen ABCC8 mutations were identified, 10 novel. Eleven patients (4 compound heterozygote, 4 single mutation, 3 no mutation detected) had diffuse hyperinsulinism. Nine patients had focal hyperinsulinism (6 single paternal mutation, 2 single mutation of undetermined parental origin, 1 none found) with absence of islet cell nuclear enlargement outside the focal area, although centroacinar cell proliferation and/or nesidiodysplasia was present in 7 cases. Regeneration after near-total pancreatectomy was documented in 4 patients, with aggregates of endocrine tissue observed at subsequent operations in 3. Although the absence of enlarged islet cell nuclei is a useful discriminant of focal hyperinsulinism associated with a paternal ABCC8 mutation, further research is needed to understand the pathophysiology of other histological abnormalities in patients with HI, which may have implications for mechanisms of ductal and islet cell proliferation. Previous surgery should be taken into account when interpreting pancreatic histology.

Multiple ectopic lesions of focal islet adenomatosis identified by positron emission tomography scan in an infant with congenital hyperinsulinism

Congenital hyperinsulinism (HI) exists in 2 histologic forms, focal and diffuse, and rarely has been attributed to lesions in ectopic pancreatic tissue. The ability to distinguish focal from diffuse HI and locate focal lesions has been difficult, thus limiting the optimal management of HI. We present a case of HI resulting from focal pancreatic and ectopic pancreatic lesions. After a near-total pancreatectomy failed to improve the patient's condition, a positron emission tomography (PET) scan performed with 18F-fluoro-L-dihydroxyphenylalanine demonstrated a focal lesion remaining in the head of the pancreas as well as 4 hot spots inferior to the remaining pancreas. Surgical exploration found pancreatic rests in the jejunum responsible for the hot spots seen on PET. Resection of the remainder of the pancreas as well as the small intestinal lesions resulted in correction of the patient's HI. Pathology confirmed the presence of focal HI lesions in the pancreatic head and small intestinal specimens. This case supports the ability of ectopic pancreatic tissue to contribute to the pathology of HI. It highlights the ability of PET to successfully identify focal lesions, including ectopic tissue, responsible for hyperinsulinemic hypoglycemia.

Frozen section examination of liver, gallbladder, and pancreas

CONTEXT

Frozen section of the liver is a comparatively frequent request that most often applies to a relatively limited number of situations. The only indication for frozen tissue examination of a gallbladder with any frequency is the presence of a polypoid mucosal lesion or a suspicious thickening of the gallbladder wall. A variety of intraoperative consultations may be applicable during surgery of the pancreas.

OBJECTIVE

To examine the indications and pitfalls regarding the gross examination and frozen section performance for liver, gallbladder, and pancreas.

DATA SOURCES

Author experience and review of the pertinent literature.

CONCLUSIONS

Although indications are relatively straightforward for frozen section of liver and gallbladder, handling of the pancreas specimens for frozen tissue examination is often a cause for a certain degree of anxiety. This situation is the result of a relative rarity of such specimens outside large tertiary referral medical centers coupled with a variety of confounding factors, including the presence of chronic pancreatitis with distortion of the normal structures and the frequent presence of variable degrees of dysplasia. The suboptimal preservation of the frozen tissue adds further angst to the scenario. In this article, the main issues are critically examined in light of the experience of the author and others.

Molecular and immunohistochemical analyses of the focal form of congenital hyperinsulinism

Congenital hyperinsulinism is a rare pancreatic endocrine cell disorder that has been categorized histologically into diffuse and focal forms. In focal hyperinsulinism, the pancreas contains a focus of endocrine cell adenomatous hyperplasia, and the patients have been reported to possess paternally inherited mutations of the ABCC8 and KCNJ11 genes, which encode subunits of an ATP-sensitive potassium channel (K(ATP)). In addition, the hyperplastic endocrine cells show loss of maternal 11p15, where imprinted genes such as p57(kip2) reside. In order to evaluate whether all cases of focal hyperinsulinism are caused by this mechanism, 56 pancreatectomy specimens with focal hyperinsulinism were tested for the loss of maternal allele by two methods: immunohistochemistry for p57(kip2) (n=56) and microsatellite marker analysis (n=27). Additionally, 49 patients were analyzed for K(ATP) mutations. Out of 56 focal lesions, 48 demonstrated clear loss of p57(kip2) expression by immunohistochemistry. The other eight lesions similarly showed no nuclear labeling, but the available tissue was not ideal for definitive interpretation. Five of these eight patients had paternal K(ATP) mutations, of which four demonstrated loss of maternal 11p15 within the lesion by microsatellite marker analysis. All of the other three without a paternal K(ATP) mutation showed loss of maternal 11p15. K(ATP) mutation analysis identified 32/49 cases with paternal mutations. There were seven patients with nonmaternal mutations whose paternal DNA material was not available, and one patient with a mutation that was not present in either parent's DNA. These eight patients showed either loss of p57(kip2) expression or loss of maternal 11p15 region by microsatellite marker analysis, as did the remaining nine patients with no identifiable K(ATP) coding region mutations. The combined results from the immunohistochemical and molecular methods indicate that maternal 11p15 loss together with paternal K(ATP) mutation is the predominant causative mechanism of focal hyperinsulinism.