Value of intra-arterial calcium stimulated venous sampling for regionalization of pancreatic insulinomas

A Case of Pancreatic Neuroendocrine Tumor with Liver Metastases Demonstrating the Possibility of Enhanced ACTH Production by the SACI Test

Objective

ACTH-producing pancreatic NETs have a propensity to metastasize, and in patients with metastases, there is no established method yet to precisely determine if the excess ACTH is produced by the primary or the metastatic tumors. Localizing the source of production of ACTH in such cases is important for devising suitable treatment strategies and evaluating the benefit of local therapies from the viewpoint of control of Cushing's syndrome.

Methods

We performed the selective arterial calcium injection (SACI) test combined with selective portal and hepatic venous sampling in a 32-year-old female patient with ectopic ACTH-producing pancreatic NET and liver metastases.

Results

The blood level of ACTH after Ca loading was significantly elevated only in the vessels thought to be directly feeding the pancreatic tumor, and Ca loading from any artery did not significantly increase ACTH concentrations in the hepatic veins compared to the main trunk of the portal vein.

Conclusions

The present case demonstrates that there might be an ACTH-producing p-NET that responds to Ca loading. Further in vitro studies are required to validate this possibility.

[Indication and Surgical Procedures for MEN1-associated Duodenopancreatic Neuroendocrine Neoplasms]

The optimal therapy of duodenopancreatic neuroendocrine neoplasia (dpNEN), which occurs in the context of multiple endocrine neoplasia type 1, is still a major challenge and is controversial. Due to the rarity of the disease, there is a lack of prospective randomised studies, so that most recommendations regarding the surgical indication and procedure are based on retrospective case series. In summary, surgical therapy is indicated for non-functional dpNEN > 2 cm, suspected malignancy and functionally active dpNEN. Enucleation or formal pancreatic resections with or without lymphadenectomy may be considered. The aim of therapy should be to eliminate hormone-associated symptoms and prevent an aggressive metastatic disease. At the same time, pancreatic function and quality of life should be preserved in the mostly young patients by resections that save as much parenchyma as possible.

Occult insulinoma with treatment refractory, severe hypoglycaemia in multiple endocrine neoplasia type 1 syndrome; difficulties faced during diagnosis, localization and management; a case report

BACKGROUND

Multiple endocrine neoplasia type 1 (MEN 1) syndrome is a rare, complex genetic disorder characterized by increased predisposition to tumorigenesis in multiple endocrine and non-endocrine tissues. Diagnosis and management of MEN 1 syndrome is challenging due to its vast heterogeneity in clinical presentation.

CASE PRESENTATION

A 23-year-old female, previously diagnosed with Polycystic Ovarian Syndrome (PCOS) and pituitary microprolactinoma presented with drowsiness,confusion and profuse sweating developing over a period of one day. It was preceded by fluctuating, hallucinatory behavior for two weeks duration. There was recent increase in appetite with significant weight gain. There was no fever, seizures or symptoms suggestive of meningism. Her Body mass index(BMI) was 32 kg/m2.She had signs of hyperandrogenism. Multiple cutaneous collagenomas were noted on anterior chest and abdominal wall. Her Glasgow Coma Scale was 9/15. Pupils were sluggishly reactive to light. Tendon reflexes were exaggerated with up going planter reflexes. Moderate hepatomegaly was present. Rest of the clinical examination was normal. Laboratory evaluation confirmed endogenous hyperinsulinaemic hypoglycaemia suggestive of an insulinoma. Hypercalcemia with elevated parathyroid hormone level suggested a parathyroid adenoma. Presence of insulinoma, primary hyperparathyroidism and pituitary microadenoma, in 3rd decade of life with characteristic cutaneous tumours was suggestive of a clinical diagnosis of MEN 1 syndrome. Recurrent, severe hypoglycaemia complicated with hypoglycaemic encephalopathy refractory to continuous, parenteral glucose supplementation and optimal pharmacotherapy complicated the clinical course. Insulinoma was localized with selective arterial calcium stimulation test. Distal pancreatectomy and four gland parathyroidectomy was performed leading to resolution of symptoms.

CONCLUSIONS

Renal calculi or characteristic cutaneous lesions might be the only forewarning clinical manifestations of an undiagnosed MEN 1 syndrome impending a life-threatening presentation. Comprehensive management of MEN 1 syndrome requires multi-disciplinary approach with advanced imaging modalities, advanced surgical procedures and long-term follow up due to its heterogeneous presentation and the varying severity depending on the disease phenotype.

Essentials of Insulinoma Localization with Selective Arterial Calcium Stimulation and Hepatic Venous Sampling

Insulinomas are the most common functional pancreatic neuroendocrine tumor. Most insulinomas can be localized non-invasively with cross-sectional and nuclear imaging. Selective arterial calcium stimulation and hepatic venous sampling is an effective and safe minimally-invasive procedure for insulinoma localization that may be utilized when non-invasive techniques are inconclusive. The procedure’s technical success and proper interpretation of its results is dependent on the interventional radiologist’s knowledge of normal and variant pancreatic arterial perfusion. Accurate pre-operative localization aids in successful surgical resection. Technical and anatomic considerations of insulinoma localization with selective arterial calcium stimulation and hepatic venous sampling are reviewed.

An Interventionist's Guide to Endocrine Consultations

Endocrinopathies are a heterogeneous group of disorders often resulting from pathologic sources of hormone production. When the clinical scenario, laboratory testing, and noninvasive imaging fail to aid confident identification of the source of hormone excess, endocrine venous sampling may localize obscure lesions to guide subsequent treatment. Knowledge of basic hormone signaling pathways, common pathophysiologic disruptions of these pathways, and serologic evaluation fosters informed conversations with referring physicians and effective patient selection. Success in the angiography suite requires familiarity with normal and variant anatomy of the multiple organs of the endocrine system, patient preparation, stimulation and sampling techniques, specimen handling, and results interpretation. ^©RSNA, 2017.

Should the Selective Arterial Secretagogue Injection Test for Insulinoma Localization Be Evaluated at 60 or 120 Seconds?

Objective The selective arterial secretagogue injection (SASI) test is considered indispensable for the accurate localization of insulinoma. However, the optimum timing of the post-injection evaluation is controversial, as some studies recommend 60 seconds [SASI (60 seconds)] while others support 120 seconds [SASI (120 seconds)]. The aim of this study was to determine the optimum timing for the SASI test evaluation for insulinoma localization. Methods Thirteen patients with surgically proven insulinoma were studied retrospectively. For the SASI test, immunoreactive insulin (IRI) was determined at baseline and at 30, 60, 90, and 120 seconds after calcium gluconate injection. A two-fold or greater increase in IRI over the baseline value was considered positive. The localization abilities of SASI (60 seconds) and SASI (120 seconds) were then compared. Results In 13 patients, a secretagogue was injected into 40 arteries supplying the pancreas. In the SASI (60 seconds) and SASI (120 seconds), the respective findings were as follows: positive predictive value, 72.2% and 68.2%; false positive rate, 25.0% and 35.0%; and rate of positivity in the head and body/tail, 38.5% and 46.2%. When the artery with the largest change was taken as the dominant artery, the localization detection sensitivity was 76.9% for SASI (60 seconds) and 92.3% for SASI (120 seconds). The sensitivity of morphological imaging techniques for localization ranged from 61.5-91.7%. Conclusion Compared with SASI (60 seconds) or morphological imaging, the insulinoma localization ability of SASI (120 seconds) was superior. Given these findings, we believe that the IRI level should be measured at 120 seconds in the SASI test.

Efficacy of laparoscopic ultrasonography in laparoscopic resection of insulinoma

Insulinoma is the most common functioning islet cell tumor of the pancreas, with an annual incidence of 4 cases/1 million individuals. It is treated by surgical methods. Open surgery was once considered the standard approach for the treatment of insulinoma. However, the procedure is traumatic and requires a large incision, which does not satisfy the growing expectations of minimally invasive management of small-sized tumors. Insulinomas are usually benign solitary tumors and mostly occur sporadically, which makes them suitable candidates for laparoscopic management. The potential advantages of laparoscopic management of insulinoma over open surgery include shorter duration of hospitalization, quicker recovery, and better cosmetic effect. However, because of the small tumor size as well as the depth and uncertainty of the location of the tumor, laparoscopic localization of the lesion without tactile sensation is difficult. Laparoscopic ultrasonography can detect about 90% of insulinomas, and its sensitivity is comparable to that of manual palpation along with intraoperative ultrasonography during open surgery; thus, it ensures the feasibility of laparoscopic management of insulinoma and reinforces its advantage as a minimally invasive procedure. Laparoscopic ultrasonography is vital for the localization of insulinomas and characterization of the surrounding pancreatic structure and should, therefore, be considered an integral part of the laparoscopic management of insulinoma.

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.

Pancreatic neuroendocrine tumors: contemporary diagnosis and management

Pancreatic neuroendocrine tumors (PNETs) are neoplasms that arise from the hormone producing cells of the islets of Langerhans, also known as pancreatic islet cells. PNETs are considered a subgroup of neuroendocrine tumors, and have unique biology, natural history and clinical management. These tumors are classified as 'functional' or 'non-functional' depending on whether they release peptide hormones that produce specific hormone- related symptoms, usually in established patterns based on tumor subtype. This manuscript will review pancreatic neuroendocrine tumor subtypes, syndromes, diagnosis, and clinical management.

Imaging in multiple endocrine neoplasia type 1: recent studies show enhanced sensitivities but increased controversies

In multiple endocrine neoplasia type 1 (MEN1) patients, a number of recent studies compare the ability of different, new imaging modalities to existing modalities to localize the important neuroendocrine tumors (NETs) that contribute to their decreased life expectancy (pancreatic NETs [pNETs] and thymic carcinoids). These included the use of 68Ga-DOTATOC-PET/CT, endoscopic ultrasound and MRI. The current paper analyzes these results in light of current guidelines and controversies involved in the treatment/management of MEN1 patients. Particular attention is paid to results in these studies with thymic carcinoids and nonfunctional pNETs/gastrinomas, which recent studies show are particularly important in determining long-term survival. These studies show a number of promising imaging results but also raise a number of controversies, which will need to be addressed both in their use initially and for serial studies in these patients.

LOCALIZATION OF PANCREATIC INSULINOMAS WITH ARTERIAL STIMULATION BY CALCIUM AND HEPATIC VENOUS SAMPLING - PRESENTATION OF A SINGLE CENTRE EXPERIENCE

Context

Arterial stimulation and venous sampling (ASVS) is the most sensitive diagnostic method for occult insulinoma localization. We present our experience with this method and modifications used that proved to ensure greater safety and sensitivity with this rare pathology. Relationship between tumour size and changes in peak insulin values and release curves were also tested.

Subjects and methods

Six consecutive patients with biochemically established diagnosis of endogenous hyperinsulinism underwent preoperative non-invasive diagnostic tests with sensitivities calculated and compared for all methods. Certain modifications were used in ASVS procedure that included hepatic vein catheterization, order of arterial stimulation, time intervals between each stimulation, diagnostic insulin gradient level and the time frame for diagnostic rise of insulin. Peak insulin values and insulin gradients were compared with tumour size in each patient.

Results

In all patients, calcium stimulation accurately localized the insulinoma, with higher sensitivity than any other method. A more than 4-fold increase in insulin level was observed in all patients, after injection into the tumour feeding artery, while 2 to 4-fold increase was observed in the tumour neighbouring areas. Tumour size showed an inversely proportional correlation to peak insulin values in each artery that correctly located the tumour.

Conclusion

ASVS presents the most accurate and safe method for localization of occult insulinomas. A four-fold insulin gradient can be used as a limit for positive preoperative localization in order to secure a higher specificity.

Incremental benefit of preoperative EUS for the detection of pancreatic neuroendocrine tumors: a meta-analysis

BACKGROUND

Current guidelines recommend CT scan or magnetic resonance imaging as the initial imaging modalities for the work-up of suspected pancreatic neuroendocrine tumors (PNETs).

OBJECTIVE

To determine the incremental benefit of preoperative EUS (IBEUS) for the detection of suspected PNETs after other investigative modalities have been attempted.

DESIGN

This systematic review searched MEDLINE, EMBASE, bibliographies of included articles, and conference proceedings for studies reporting original data regarding the preoperative detection of PNETs. Pooled IBEUS was calculated by using random effects models. Heterogeneity was explored by using stratified meta-analysis and meta-regression. Evidence of small-study effects was assessed by using funnel plots and the Begg test.

PATIENTS

Patients with suspected PNETs.

INTERVENTIONS

EUS evaluation.

MAIN OUTCOME MEASUREMENTS

The pooled IBEUS for the detection of PNETs after CT scan, with or without additional investigative modalities.

RESULTS

Among 4505 citations identified, we included 17 cohort studies (612 patients). EUS identified PNETs in 97% of cases. Improved PNET identification with EUS was observed in all of the studies. After adjusting for small-study effects, meta-analysis showed that EUS alone could identify PNETs in approximately 1 in 4 patients (adjusted IBEUS 26%; 95% confidence interval, 17%-37%). The pooled IBEUS varied based on the study design, study size, type of CT scan used, and the number of modalities used prior to EUS.

LIMITATIONS

The majority of included studies were retrospective. Small-study effects were observed.

CONCLUSION

Preoperative EUS is associated with an increase in PNET detection after other modalities are attempted.

Intra-arterial calcium stimulation test with hepatic venous sampling for preoperative diagnosis of a large insulinoma in an obese young man

Herein, we report the case of a large benign insulinoma in an obese young man with a three-year history of asymptomatic hypoglycaemia. He presented to our outpatient department with a two-week history of dizziness and morning cold sweats. A random serum glucose test revealed hypoglycaemia. Upon admission, computed tomography and magnetic resonance imaging of the abdomen with intravenous contrast media showed an enhancing mass lesion in the uncinate process of the pancreas. To confirm the diagnosis, an intra-arterial calcium stimulation test with hepatic venous sampling was performed for preoperative localisation and to exclude the presence of occult insulinomas. The patient underwent an exploratory laparotomy, with successful resection of the pancreatic head tumour. Histology confirmed the diagnosis of insulinoma. The patient's postoperative recovery was uneventful, and he has not developed further episodes of hypoglycaemia three years post surgery.

GEP-NETS update: functional localisation and scintigraphy in neuroendocrine tumours of the gastrointestinal tract and pancreas (GEP-NETs)

For patients with neuroendocrine tumours (NETs) of the gastrointestinal tract and pancreas (GEP) (GEP-NETs), excellent care should ideally be provided by a multidisciplinary team of skilled health care professionals. In these patients, a combination of nuclear medicine imaging and conventional radiological imaging techniques is usually mandatory for primary tumour visualisation, tumour staging and evaluation of treatment. In specific cases, as in patients with occult insulinomas, sampling procedures can provide a clue as to where to localise the insulin-hypersecreting pancreatic NETs. Recent developments in these fields have led to an increase in the detection rate of primary GEP-NETs and their metastatic deposits. Radiopharmaceuticals targeted at specific tumour cell properties and processes can be used to provide sensitive and specific whole-body imaging. Functional imaging also allows for patient selection for receptor-based therapies and prediction of the efficacy of such therapies. Positron emission tomography/computed tomography (CT) and single-photon emission CT/CT are used to map functional images with anatomical localisations. As a result, tumour imaging and tumour follow-up strategies can be optimised for every individual GEP-NET patient. In some cases, functional imaging might give indications with regard to future tumour behaviour and prognosis.

Comparison of two low-dose calcium infusion schedules for localization of insulinomas by selective pancreatic arterial injection with hepatic venous sampling for insulin

OBJECTIVE

Localization of small insulinomas may be difficult. Selective pancreatic arterial injection of calcium with hepatic venous insulin measurement (SACST) has been used for this purpose, but can rarely cause hypoglycaemia. Two low-dose concentrations of calcium, 0·25 and 0·1 of the usual concentration used for the test, have been compared for sensitivity of localization and safety.

DESIGN

Selective pancreatic arterial injection of calcium with hepatic venous insulin measurement was performed at calcium concentrations of 0·0025 (Protocol A) and 0·00625 (Protocol B) mEq calcium per kg. The standard concentration is 0·025 mEq/kg.

PATIENTS

Twenty one successive patients with biochemical evidence of insulinoma were studied.

RESULTS

Using surgical localization as the gold standard, Protocol A had a sensitivity of 91% and Protocol B 75% for correct localization. The false-positive localization rate was 16%. No hypoglycaemia was observed. These results compare favourably with published data using the standard calcium concentration. Selective pancreatic arterial injection of calcium with hepatic venous insulin measurement was superior to localization by noninvasive imaging; in seven cases, SACST was correct when conventional imaging was negative (five) or false positive (two).

CONCLUSION

Low concentrations of calcium are effective and safe when performing SACST for localization of insulinoma.

Causes of death and prognostic factors in multiple endocrine neoplasia type 1: a prospective study: comparison of 106 MEN1/Zollinger-Ellison syndrome patients with 1613 literature MEN1 patients with or without pancreatic endocrine tumors

Multiple endocrine neoplasia type 1 (MEN1) is classically characterized by the development of functional or nonfunctional hyperplasia or tumors in endocrine tissues (parathyroid, pancreas, pituitary, adrenal). Because effective treatments have been developed for the hormone excess state, which was a major cause of death in these patients in the past, coupled with the recognition that nonendocrine tumors increasingly develop late in the disease course, the natural history of the disease has changed. An understanding of the current causes of death is important to tailor treatment for these patients and to help identify prognostic factors; however, it is generally lacking.To add to our understanding, we conducted a detailed analysis of the causes of death and prognostic factors from a prospective long-term National Institutes of Health (NIH) study of 106 MEN1 patients with pancreatic endocrine tumors with Zollinger-Ellison syndrome (MEN1/ZES patients) and compared our results to those from the pooled literature data of 227 patients with MEN1 with pancreatic endocrine tumors (MEN1/PET patients) reported in case reports or small series, and to 1386 patients reported in large MEN1 literature series. In the NIH series over a mean follow-up of 24.5 years, 24 (23%) patients died (14 MEN1-related and 10 non-MEN1-related deaths). Comparing the causes of death with the results from the 227 patients in the pooled literature series, we found that no patients died of acute complications due to acid hypersecretion, and 8%-14% died of other hormone excess causes, which is similar to the results in 10 large MEN1 literature series published since 1995. In the 2 series (the NIH and pooled literature series), two-thirds of patients died from an MEN1-related cause and one-third from a non-MEN1-related cause, which agrees with the mean values reported in 10 large MEN1 series in the literature, although in the literature the causes of death varied widely. In the NIH and pooled literature series, the main causes of MEN1-related deaths were due to the malignant nature of the PETs, followed by the malignant nature of thymic carcinoid tumors. These results differ from the results of a number of the literature series, especially those reported before the 1990s. The causes of non-MEN1-related death for the 2 series, in decreasing frequency, were cardiovascular disease, other nonendocrine tumors > lung diseases, cerebrovascular diseases. The most frequent non-MEN1-related tumor deaths were colorectal, renal > lung > breast, oropharyngeal. Although both overall and disease-related survival are better than in the past (30-yr survival of NIH series: 82% overall, 88% disease-related), the mean age at death was 55 years, which is younger than expected for the general population.Detailed analysis of causes of death correlated with clinical, laboratory, and tumor characteristics of patients in the 2 series allowed identification of a number of prognostic factors. Poor prognostic factors included higher fasting gastrin levels, presence of other functional hormonal syndromes, need for >3 parathyroidectomies, presence of liver metastases or distant metastases, aggressive PET growth, large PETs, or the development of new lesions.The results of this study have helped define the causes of death of MEN1 patients at present, and have enabled us to identify a number of prognostic factors that should be helpful in tailoring treatment for these patients for both short- and long-term management, as well as in directing research efforts to better define the natural history of the disease and the most important factors determining long-term survival at present.

Multifocal lesions with pancreatic atrophy in IgG4-related autoimmune pancreatitis: report of a case

We herein report a case of IgG4-related autoimmune pancreatitis (AIP). A 72-year-old male with jaundice visited our hospital complaining of epigastralgia. A blood chemistry analysis revealed elevated serum levels of total bilirubin and DUPAN-II. Computed tomography (CT) revealed irregularly shaped pancreatic masses with a stricture of the main pancreatic duct (MPD) in the head and tail that were interposed by marked atrophy with MPD dilation in the body. F-18 fluorodeoxyglucose (FDG)-positron emission tomography/CT revealed abnormally intense FDG uptake only at the masses. During surgery, another small tumor was also found in the atrophied body; therefore, a total pancreatectomy was performed under the diagnosis of multiple pancreatic cancers. The histological analysis revealed fibrosis with dense and diffuse infiltrations of lymphocytes and IgG4-positive plasma cells. The pancreatic parenchyma of the body was firmly replaced by fibrosis. AIP can lead to the formation of multiple pancreatic lesions, and thus the correct diagnosis is occasionally difficult to establish in atypical cases.

Insulinoma and anaesthetic implications

Insulinoma is a rare neuroendocrine tumour of the pancreas , which is usually small, solitary and benign. It may be part of the multiple endocrine neoplasia type 1 syndrome. It is diagnosed by clinical, biochemical and imaging modalities. Hypoglycaemic symptoms can be medically controlled by diazoxide or somatostatin analogues. Localisation of the tumour is a challenge to clinicians. Surgical resection is the curative treatment with a high success rate. Intraoperatively, ultrasound and surgical palpation help to confirm the site of tumour. Intraoperatively, maintenance of optimum glucose levels is of main concern because there may be severe hypoglycemia while handling the tumour, symptoms of which remain masked under general anaesthesia. Glucose infusion and frequent plasma glucose monitoring to maintain plasma glucose level more than 60 mg/dL is found to be helpful. We performed a systematic search in PubMed, Cochrane Library and also in Google. We used the following text words for our search: Insulinoma, neuro-endocrine tumors, multiple endocrine neoplasia, hypoglycemia, anaesthetic management of insulinoma, glucose management. In this article, we review the incidence and epidemiology of insulinoma, its clinical features, diagnosis, localisation and treatment, with special emphasis on anaesthetic management.

Octreotide-treated diabetes accompanied by endogenous hyperinsulinemic hypoglycemia and protein-losing gastroenteropathy

Occurrence of hypoglycemia in diabetes patients is very rare. We report here a case of frequent hypoglycemic attacks caused by inappropriate endogenous hyperinsulinemia in a female patient with poorly controlled diabetes and protein-losing gastroenteropathy. The blood glucose profiles of the patient were unstable. Results of the fasting test performed to investigate the cause of hypoglycemia suggested endogenous hyperinsulinism. Repeated selective arterial calcium injection tests suggested that hyperinsulinemia might be extrapancreatic in origin. However, efforts to detect a responsible lesion such as insulinoma were unsuccessful. Octreotide was used for the treatment of hypoglycemia and protein-losing gastroenteropathy. After treatment, although her leg edema caused by hypoalbuminemia persisted, hypoglycemia almost disappeared.

[Invasive diagnostic procedures for insulinomas of the pancreas]

Insulinomas are the most common cause for hypoglycemia with endogenous hyperinsulinism. Insulinomas are the most frequent endocrine tumor of the pancreas and 10% occur as multiple tumors (e.g. multiple endocrine neoplasia type I) or in rare cases as islet cell hyperplasia. A further 10-15% of insulinomas are malignant. Non-invasive imaging modalities, such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and somatoreceptor scintigraphy (SRN) show a lower sensitivity for detection and localization of tumors, because in many cases insulinomas are smaller than 2 cm in size. Invasive pre-operative diagnostic procedures, such as transhepatic peripancreatic venous blood sampling (TPVB) and the intra-arterial calcium stimulation test (ASVS) are much more time-intensive compared to CT, MRI and US with an examination time of 2-3 h but achieve a more exact pre-operative detection and localization with sensitivities mostly greater than 95% and are therefore the diagnostic methods of choice.

Accurate preoperative localization of insulinomas avoids the need for blind resection and reoperation: analysis of a single institution experience with 17 surgically treated tumors over 19 years

INTRODUCTION

Presently, the need for and choice of preoperative localization tests for insulinomas remain controversial. We report the results from a single institution experience whereby the management policy adopted was that of accurate preoperative localization before surgical exploration.

MATERIALS AND METHODS

From 1990 to 2008, 17 patients with a clinical and biochemical diagnosis of an insulinoma who underwent surgery were retrospectively reviewed. The diagnosis of all insulinomas were confirmed pathologically.

RESULTS

All tumors were localized preoperatively and an average of 2.2 preoperative localization studies including 1.4 noninvasive studies and 0.8 invasive studies were utilized per patient. Invasive localization modalities were more sensitive (92%) than noninvasive modalities in localizing insulinomas (71%). Intra-arterial calcium stimulation with hepatic venous sampling was the most sensitive invasive modality (100%), whereas magnetic resonance imaging was the most sensitive noninvasive modality (63%). Fifteen of 17 tumors (88%) were localized intraoperatively via inspection/palpation and/or intraoperative ultrasonography. Both insulinomas which were not localized intraoperatively were localized correctly to the distal pancreas via preoperative transhepatic portal venous sampling. None of the patients required a blind resection or surgical reexploration for failed localization. All 17 patients underwent complete surgical resection which included eight enucleations and nine distal pancreatectomies with a cure rate of 94% (16/17) at a median follow-up of 35 (range, 1-217) months. The postoperative morbidity and long-term outcome of enucleation was similar to distal pancreatectomy despite a higher rate of microscopic margin involvement.

CONCLUSION

Accurate preoperative localization of insulinomas is useful as it eliminates the need for blind distal pancreatectomy and avoids reoperation. Complete surgical resection is the treatment of choice, and whenever possible, a pancreas-sparing approach such as enucleation should be adopted.

Gastrointestinal neuroendocrine tumors: pancreatic endocrine tumors

Pancreatic endocrine tumors (PETs) have long fascinated clinicians and investigators despite their relative rarity. Their clinical presentation varies depending on whether the tumor is functional or not, and also according to the specific hormonal syndrome produced. Tumors may be sporadic or inherited, but little is known about their molecular pathology, especially the sporadic forms. Chromogranin A appears to be the most useful serum marker for diagnosis, staging, and monitoring. Initially, therapy should be directed at the hormonal syndrome because this has the major initial impact on the patient's health. Most PETs are relatively indolent but ultimately malignant, except for insulinomas, which predominantly are benign. Surgery is the only modality that offers the possibility of cure, although it generally is noncurative in patients with Zollinger-Ellison syndrome or nonfunctional PETs with multiple endocrine neoplasia-type 1. Preoperative staging of disease extent is necessary to determine the likelihood of complete resection although debulking surgery often is believed to be useful in patients with unresectable tumors. Once metastatic, biotherapy is usually the first modality used because it generally is well tolerated. Systemic or regional therapies generally are reserved until symptoms occur or tumor growth is rapid. Recently, a number of newer agents, as well as receptor-directed radiotherapy, are being evaluated for patients with advanced disease. This review addresses a number of recent advances regarding the molecular pathology, diagnosis, localization, and management of PETs including discussion of peptide-receptor radionuclide therapy and other novel antitumor approaches. We conclude with a discussion of future directions and unsettled problems in the field.

Surgical approach and perioperative complications determine short-term outcomes in patients with insulinoma: results of a bi-institutional study

BACKGROUND

Despite advancements in radiologic imaging and minimally invasive surgery, the evaluation and management of insulinomas is institution and surgeon dependent. Therefore, the reported surgical outcomes are highly variable. We compared the surgical management and outcomes of insulinomas between two international tertiary-care surgical units to better identify the best management as determined by short-term outcomes.

METHODS

We performed a retrospective review of patients who underwent surgery for insulinomas over a 117-month period at UT Southwestern Medical Center in Dallas (UTSW) and Queen Mary Hospital in Hong Kong (QMHK). Data collected included imaging studies, operative procedure, complications, and outcomes.

RESULTS

Thirty-seven patients were identified. Preoperative localization by computed tomography (CT) scan was successful in 21 patients (63.9%). In Hong Kong, 16 patients underwent selective arterial cannulation and calcium stimulation (SACST) with a success rate of 87.5%. Surgical management consisted of enucleation in 24 patients and distal pancreatectomy in 13 patients. Thirty patients underwent a concurrent intraoperative ultrasound, with localization in 96.7%. Laparoscopic procedures were accomplished in 20 patients. Nine postoperative complications were identified, four occurring in the laparoscopic group. Patients undergoing laparoscopic procedures had a decreased length-of-stay (LOS) compared with patients undergoing an open procedure and patients who had uncomplicated surgery had a trend toward decreased LOS.

CONCLUSION

Though the accuracy of CT scans for localizing insulinomas is only 64%, the addition of SACST or intraoperative ultrasound and pancreatic palpation increases accuracy to 97.1%. Compared with open procedures, laparoscopic resection is associated with comparable complication rates and shorter hospital length of stay.

Insulinoma cell calcium-sensing receptor influences insulin secretion in a case with concurrent familial hypocalciuric hypercalcemia and malignant metastatic insulinoma

CONTEXT AND OBJECTIVE

Arterial stimulation and venous sampling (ASVS) is an important technique for localizing insulinoma. The principle behind ASVS is that insulin secretion is promoted from insulinoma cells by the injection of calcium into the insulinoma-feeding artery. However, the mechanism for ASVS-induced insulin secretion remains unclear. Both insulinoma and familial hypocalciuric hypercalcemia (FHH) are rare diseases. This study reports on a case in which both of these diseases occur concurrently.

DESIGN AND PATIENT

The patient with FHH also suffered from insulinoma. We reasoned that insulin secretion for ASVS is dependent on the calcium-sensing receptor (CaSR). ASVS was performed on this patient. The expression of the CaSR protein and corresponding mRNA were confirmed.

RESULTS

No significant changes in the plasma levels of insulin and C-peptide were observed during ASVS. The patient was clinically diagnosed as having FHH. We confirmed that a mutation in the CaSR gene was present in the genomic DNA of this patient and that there were no mutations in the multiple endocrine neoplasia type 1 gene. In addition, expression of both CaSR mRNA and CaSR protein was confirmed in the insulinoma samples.

CONCLUSION

These results suggest that the CaSR gene is involved in ASVS-induced insulin secretion.

Occult sporadic insulinoma: localization and surgical strategy

Insulinomas continue to pose a diagnostic challenge to physicians, surgeons and radiologists alike. Most are intrapancreatic, benign and solitary. Biochemical diagnosis is obtained and imaging techniques to localize lesions continue to evolve. Surgical resection is the treatment of choice. Despite all efforts, an occult insulinoma (occult insulinoma refers to a biochemically proven tumor with indeterminate anatomical site before operation) may still be encountered. New localization preoperative techniques decreases occult cases and the knowledge of the site of the mass before surgery allows to determine whether enucleation of the tumor or pancreatic resection is likely to be required and whether the tumor is amenable to removal via a laparoscopic approach. In absence of preoperative localization and intraoperative detection of an insulinoma, blind pancreatic resection is not recommended.

Pancreatic neuroendocrine tumours

Pancreatic neuroendocrine tumours (PET) are rare neoplasms of the pancreas accounting for less than 5% of all primary pancreatic malignancies. Included in this group are insulinomas, gastrinomas, glucagonoma and somatostatinomas. Collectively these neoplasms are classified as functional PETs. Where a PET is not associated with a clinical syndrome due to hormone oversecretion, it is referred to as a non-functioning PET. Non-functioning PETs are pancreatic tumours with endocrine differentiation but lack a clinical syndrome of hormone hypersecretion. The incidence of these tumours varied between 15 and 53%. Presentation is related to the mass effect of the tumour with symptoms often non-specific. Treatment is surgical excision with chemotherapy and hormonal therapy is controversial. For functioning PETs, surgery remains the optimal therapy, however, long-term survival can be expected even in the presence of metastases. With advances in medical management, radiolabelled somatostatin therapy, hepatic arterial chemoembolisation and radiofrequency ablation, symptoms may be controlled to optimize quality of life.

Rapid intraoperative insulin assay: a novel method to differentiate insulinoma from nesidioblastosis in the pediatric patient

Introduction

Hyperinsulinism is the most common cause of recurrent and persistent hypoglycemia in infancy and childhood. Causes can include nesidioblastosis, pancreatic islet cell tumors such as insulinoma, and associations with multiple endocrine neoplasia syndromes. Although new, improved imaging techniques have allowed for more precise preoperative localization of insulinomas, the differentiation of nesidioblastosis and insulinoma, particularly in children, can be challenging. To improve intraoperative localization and confirmation of successful resection of insulinoma, a novel hormonal assay, the rapid intraoperative insulin assay, is reported for the first time in a pediatric patient. This intraoperative radioimmunoassay for insulin yields results within several minutes and confirms complete resection of insulinoma.

Case description

We present a case of pancreatic insulinoma in a child with symptoms of severe hypoglycemia, causing seizures. The insulinoma was enucleated laparoscopically, and rapid intra-operative insulin assay used to determine the success of the procedure.

Discussion and evaluation

This rapid intra-operative test provides a valuable adjunct for determining complete excision in complicated cases of recurrent or questionable insulinoma. Although not a common problem, for pediatric patients in whom the diagnosis is not clear, this test may provide a novel approach to confirming disease.

Conclusion

We propose the use of this assay in facilitating intra-operative resection and confirmation of complete excision in pediatric patients. This population may especially benefit from this novel assay to confirm complete resection and to differentiate multiple etiologies of hyperinsulinism.

The management of insulinoma

BACKGROUND

Insulinomas are rare tumours. Their clinical presentation, localization techniques and operative management were reviewed.

METHODS

An electronic search of the Medline, Embase and Cochrane databases was undertaken for articles published between January 1966 and June 2005 on the history, presentation, clinical evaluation, use of imaging techniques for tumour localization and operative management of insulinoma.

RESULTS AND CONCLUSION

Most insulinomas are intrapancreatic, benign and solitary. Biochemical diagnosis is obtained during a supervised 72-h fast. Non-invasive preoperative imaging techniques to localize lesions continue to evolve. Intraoperative ultrasonography can be combined with other preoperative imaging modalities to improve tumour detection. Surgical resection is the treatment of choice. In the absence of preoperative localization and intraoperative detection of an insulinoma, blind pancreatic resection is not recommended.

Angiography and arterial stimulation venous sampling in the localization of pancreatic neuroendocrine tumours

Insulin- and gastrin-secreting neuroendocrine tumours of the pancreas are often very small at presentation because of the potent effects of their hormonal outputs, and they may therefore prove difficult to localize preoperatively. This is despite the advances made in recent years in cross-sectional imaging techniques, especially multidetector-row computed tomography and endoscopic ultrasound. In this chapter the techniques of angiography and arterial stimulation venous sampling used for the localization of these neoplasms are described; a combination of these two modalities provides both anatomical and functional data that are not available with other localization techniques, thereby improving operative outcome.

Blood Glucose Control During Selective Arterial Stimulation and Venous Sampling for Localization of Focal Hyperinsulinism Lesions in Anesthetized Children

Surgical management of congenital hyperinsulinism is improved by accurate localization of small, focal dysregulated pancreatic lesions using the arterial stimulation and venous sampling (ASVS) test, which can demonstrate increased hepatic venous insulin concentrations after selective arterial injections of calcium. However, anesthesia-related increases in blood glucose can induce insulin secretion, making it difficult to interpret ASVS test data. In this retrospective study, we examined the effect of anesthetic interventions on blood glucose concentrations in 68 children undergoing ASVS testing. We considered only the glucose concentrations observed before calcium stimulation in the final analysis. The choice of drugs for induction (sevoflurane, propofol, or thiopentone), maintenance inhaled anesthetics (sevoflurane, desflurane, or isoflurane), and the use of caudal epidural bupivacaine were not associated with significant differences in the mean blood glucose concentration before ASVS. However, patients receiving remifentanil infusions had smaller mean glucose concentrations (80 +/- 18 versus 100 +/- 44 mg x dl(-1), P = 0.01). These concentrations were also significantly smaller if tracheal intubation was delayed for at least 10 min after induction while patients received inhaled anesthetics via a face mask along with remifentanil infusions (79 +/- 14 for delayed intubation versus 95 +/- 39 mg x dl(-1) for early intubation, respectively, P = 0.03). The percentage increase in glucose concentrations from preintubation values was significantly smaller in these subjects (3.7% +/- 21.9% for delayed intubation versus 31.7% +/- 60.4% for early intubation, P = 0.02). We conclude that the anesthetic management protocol for these patients should include the use of remifentanil infusions and the administration of inhaled anesthetics and remifentanil infusions for a minimum of 10 min to establish a deep plane of anesthesia before tracheal intubation.

Utilização do estímulo superseletivo arterial com cálcio e coleta venenosa hepática (EACV) no diagnóstico pré-operatório do insulinoma: relato de caso e revisão da literatura

Insulinomas ocultos são tumores não detectáveis aos exames convencionais. O estímulo superseletivo arterial com cálcio e coleta venosa hepática (EACV) é um exame que pode ser utilizado para localizar o segmento pancreático acometido pelo tumor. Relatamos o caso de uma paciente com insulinoma oculto detectado por meio do EACV. Além disso, são discutidos aspectos técnicos da realização do exame.

Diagnosis and localization of insulinoma after negative laparotomy by hyperinsulinemic, hypoglycemic clamp and intra-arterial calcium stimulation

A 40-year-old woman with recurrent episodes of hypoglycemia was referred because of suspected insulinoma. Prolonged fasting was discontinued after 24 h due to symptomatic hypoglycemia (29 mg/dl, glucose/insulin-ratio 0.34). Magnetic resonance tomography showed a small 0.3 cm lesion in the body of the pancreas. During subsequent surgery a pancreatic tumor could not be detected, neither by manual palpation nor intraoperative ultrasonography. A hyperinsulinemic, sequentially eu- and hypoglycemic clamp confirmed the biochemical diagnosis of endogenous hyperinsulinemia and intra-arterial calcium stimulation localized calcium responsive tissue in the feeding distribution of the superior mesenteric artery. An octreotide scan was negative. During relaparotomy, six weeks after the initial surgery, the pancreatic body and tail were resected and a approximately 1 cm non-malignant insulinoma was found. Although the use of highly sensitive, and more sophisticated and expensive methods for the diagnosis and localization of insulinomas are not generally suggested, we recommend application of intra-arterial calcium stimulation if the tumor is not detected using conventional diagnostic procedures.

Intra-arterial calcium stimulation test for detection of insulinomas: detection rate, responses of pancreatic peptides, and its relationship to differentiation of tumor cells

The selective intra-arterial calcium stimulation test has greatly facilitated the precise regionalization of insulinomas smaller than 2 cm, which noninvasive techniques (ultrasound [US], computed tomography [CT], magnetic resonance imaging [MRI]) often fail to localize. This study examined not only the role of the test in the localization of insulinomas, but also the responsiveness of 3 beta-cell peptides (insulin, C peptide, and proinsulin) and their relationship to the degree of differentiation of the tumor cells, using percentage decrease of both proinsulin/insulin (P/I) and proinsulin/C peptide (P/C) ratios after stimulation as indices. Ten consecutive surgically proven insulinoma patients each received an injection of calcium into the arteries supplying the pancreas after standard selective angiography and beta-cell peptide levels were measured in samples taken from the right hepatic vein before and 30, 60, 90, 120, and 180 seconds after each injection prior to operation. After surgery, the expressions of the calcium sensing receptor (CaSR) on the resected tumors were assessed by immunohistochemistry. Intra-arterial calcium stimulation with sampling either for insulin or for C peptide correctly predicted the site of insulinoma in 8 of 9 patients or in 7 of 8 patients if the 2 big malignant insulinomas were excluded; thus, the detection rate of this test was 89% and 88%, respectively. Calcium administration stimulated a marked and prompt release of insulin and C peptide simultaneously. Both peaked within 30 to 60 seconds, then declined gradually thereafter, remaining above the baseline at 180 seconds. The magnitude of increase correlated well with the corresponding percentage decrease of P/I and P/C ratios. The response of proinsulin was much less. Immunohistochemistry demonstrated variable membraneous staining for CaSR in normal pancreatic islets and in about 9% of the total normal beta cells, whereas staining in tumor cells was only minimally detectable. We conclude that selective intra-arterial calcium stimulation with hepatic venous sampling either for insulin or for C peptide is a highly sensitive method for the preoperative localization of small insulinomas. Calcium injection stimulates a brisk response of insulin, C peptide, and proinsulin simultaneously and the magnitude of increase of both insulin and C peptide appears to be correlated well with the degree of differentiation of the tumor cells. The exact mechanism by which calcium provokes the release of beta-cell peptides is less clear and whether the CaSR is involved in the mechanism of its action requires further study.

Neuroendocrine tumors of the pancreas

BACKGROUND

The benefits of associating magnetic resonance imaging (MRI) and laparoscopy for localizing and treating neuroendocrine pancreatic tumors (NEPTs) have been poorly documented.

METHODS

In a retrospective study, eight patients with a mean age of 48 years were operated on for a NEPT. MRI was used to localize the lesions. In all patients a laparoscopic resection was carried out. Laparoscopic ultrasonography (LUS) was used during most operations.

RESULTS

The tumor was clearly localized by MRI in seven patients, and LUS showed the lesion in another patient whose preoperative MRI had been unsuitable. Three enucleations, three spleen-preserving caudal pancreatectomies, and two caudal pancreatectomies with splenectomy were carried out. There were no conversions and the mean operating time was 260 min, with a mean blood loss of 180 ml. The mean hospital stay was 7 days. There were no minor nor major complications during the hospitalization period. However, a pancreatic abscess was diagnosed in one patient 1 month later, requiring an urgent laparotomy.

CONCLUSION

MRI as well as LUS are indeed suitable techniques to localize NEPTs. Moreover, the minimally invasive approach ensured an adequate treatment with a more comfortable and short postoperative recovery.

Insulinoma accompanied by diabetes mellitus

A 53-year-old type 2 diabetic man was admitted due to spontaneous relatively hyperinsulinemic hypoglycemia. Oral glucose ingestion and arginine tolerance test showed hyperinsulinemic response. Arterial stimulation and venous sampling (ASVS) showed hyperinsulinemic response measured from the splenic artery after calcium gluconate stimulation. Diagnosis was insulinoma in the pancreas feeding from the artery. He has not suffered from spontaneous hypoglycemia since removal of the pancreatic body, tail and spleen. The specimen showed a solitary islet cell tumor. The high homeostasis model assessment of insulin resistance (HOMA-R) levels reflecting insulin resistance and hyperinsulinemic response after operation remained almost unchanged, indicating high insulin resistance and an insulin hypersecreting diabetic patient.

Selective intra-arterial calcium stimulation with hepatic venous sampling for preoperative localization of insulinomas

OBJECTIVE

To determine the value of selective intra-arterial calcium stimulation with hepatic venous sampling using serum insulin and C-peptide gradients for the preoperative localization of insulinomas.

MATERIALS AND METHODS

Seven consecutive patients (three men and four women aged 15-77 (mean, 42.7) years) with hypoglycemia underwent selective intra-arterial calcium stimulation in conjunction with hepatic venous sampling. Insulin gradients were calculated by an individual blinded to all other preoperative imaging studies and operative findings. In all patients except one, C-peptide gradients were also analyzed. The results were compared with the preoperative findings of ultrasonography, computed tomography, arteriography and endoscopic ultrasonography, as well as with the intraoperative findings of ultrasonography and palpation at surgery.

RESULTS

Eight insulinomas (mean diameter, 12.5 mm) were diagnosed after surgery. In six patients, the calcium stimulation test with insulin gradients allowed accurate localization of the pathologic source of insulin secretion. Both C-peptide and insulin gradients substantially increased diagnostic accuracy. In one patient, C-peptide gradients were more helpful than insulin gradients for tumor localization.

CONCLUSION

Selective intra-arterial calcium stimulation with hepatic venous sampling is a highly accurate and safe method for the preoperative localization of insulinomas. Additional C-peptide gradients seem to be helpful in assessing tumor location, but further study is needed.

Endocrine tumours of the pancreas: review and recent advances

Pancreatic endocrine tumours (PET) are rare but nonetheless important to recognize and treat in a timely fashion. Significant morbidity occurs due to excess secretion of hormones, with all of the PET having some degree of malignant potential. Surgeons must plan directed operative strategies to deal with these tumours and be prepared to undertake aggressive palliative debulking resections if indicated. Somatostatin receptor scintigraphy and endoscopic ultrasound have been particularly helpful in both localizing and staging patients with PET. Other important advances in management include the use of long-acting somatostatin analogues to inhibit hormonal secretion and tumour growth. The possibility of multiple endocrine neoplasia type 1 (MEN-1) should be considered in any patient with a PET. The present article will review the various classes of PET, describe MEN-1 in relation to PET and examine advances in imaging and localization. The role of surgery for PET is also discussed in the present review.