Occult sporadic insulinoma: Localization and surgical strategy

Mechanism and recent updates on insulin-related disorders

Insulin, a small protein with 51 amino acids synthesized by pancreatic β-cells, is crucial to sustain glucose homeostasis at biochemical and molecular levels. Numerous metabolic dysfunctions are related to insulin-mediated altered glucose homeostasis. One of the significant pathophysiological conditions linked to the insulin associated disorder is diabetes mellitus (DM) (type 1, type 2, and gestational). Insulin resistance (IR) is one of the major underlying causes of metabolic disorders despite its association with several physiological conditions. Metabolic syndrome (MS) is another pathophysiological condition that is associated with IR, hypertension, and obesity. Further, several other pathophysiological disorders/diseases are associated with the insulin malfunctioning, which include polycystic ovary syndrome, neuronal disorders, and cancer. Insulinomas are an uncommon type of pancreatic β-cell-derived neuroendocrine tumor that makes up 2% of all pancreatic neoplasms. Literature revealed that different biochemical events, molecular signaling pathways, microRNAs, and microbiota act as connecting links between insulin disorder and associated pathophysiology such as DM, insuloma, neurological disorder, MS, and cancer. In this review, we focus on the insulin-related disorders and the underlying mechanisms associated with the pathophysiology.

Insulinoma with peripheral neuropathy: a case report

BACKGROUND

Insulinomas are rare neuroendocrine tumors that typically present with hypoglycemic crises. Peripheral neuropathy is an uncommon complication of insulinoma. Most clinicians expect peripheral neuropathy symptoms to reverse completely after the insulin-secreting tumor is resected, but this may be a misassumption.

CASE REPORT

We report a case of a 16-year-old Brazilian boy with clonic muscle spasms of the lower limbs for almost one year. Disabling paraparesis and confusional episodes had progressively set in as well. There were no sensorial abnormalities in the lower limbs, upper limbs or cranial nerves. An electromyography revealed a motor neuropathy of the lower limbs. The diagnosis of insulinoma was established as serum insulin and C-peptide concentrations were inappropriately normal during spontaneous episodes of hypoglycemia. Following a normal abdominal magnetic resonance scan, the imaging work-up continued with an endoscopic ultrasound, which localized the tumor at the pancreatic body-tail transition. Once localized, a prompt surgical removal (enucleation) of the tumor was undertaken, leading to an immediate and complete resolution of hypoglycemia. The time length between the onset of symptoms and tumor resection was 15 months. After surgery, the symptoms of peripheral neuropathy of the lower limbs showed a slow and only partial improvement. At a two-year follow-up after surgery, although being able to lead a normal and productive life, the patient still reported symptoms of reduced muscular strength in the lower limbs and a new electroneuromyography analysis showed chronic denervation and reinnervation in the legs' muscles-indicating chronic neuropathic injury.

CONCLUSION

The events of this case reinforce the importance of an agile diagnostic work-up and spry definitive treatment for patients with this uncommon disease, enabling the cure of neuroglycopenia before permanent bothersome complications ensue.

Indocyanine green fluorescence imaging to localize insulinoma and provide three-dimensional demarcation for laparoscopic enucleation: a retrospective single-arm cohort study

BACKGROUND

Indocyanine green (ICG) fluorescence imaging is a new technology that can improve the real-time location of tumor edges and small nodules during surgery. However, no study has investigated its application in laparoscopic insulinoma enucleation. This study aimed to evaluate the feasibility and accuracy of this method for intraoperative localization of insulinomas and margin assessment during laparoscopic insulinoma enucleation.

MATERIALS AND METHODS

Eight patients who underwent laparoscopic insulinoma enucleation from October 2016 to June 2022 were enrolled. Two methods of ICG administration, ICG dynamic perfusion and three-dimensional (3D) demarcation staining, were utilized in the laparoscopic insulinoma enucleation. Tumor-to-background ratio (TBR) and histopathologic analysis were used to evaluate the feasibility and accuracy of these novel navigation methods in laparoscopic insulinoma enucleation.

RESULTS

All eight enrolled patients underwent both ICG dynamic perfusion and 3D demarcation staining. ICG dynamic perfusion images were available for six of them, among which five tumors could be recognized by TBR (largest TBR in each case 4.42±2.76), while the other could be distinguished by the disordered blood vessels in the tumor area. Seven out of eight specimens had successful 3D demarcation staining (TBR 7.62±2.62). All wound bed margins had negative frozen sections and final histopathologic diagnoses.

CONCLUSIONS

ICG dynamic perfusion may be helpful in observing the abnormal vascular perfusion of tumors, providing similar functionality to intraoperative real-time angiography. ICG injection under the tumor pseudocapsule may be a useful method for acquiring real-time, 3D demarcation for the resection of insulinoma.

Identification and Validation of a New Peptide Targeting Pancreatic Beta Cells

Noninvasive targeted visualization of pancreatic beta cells or islets is becoming the focus of molecular imaging application in diabetes and islet transplantation studies. In this study, we aimed to produce the beta-cell-targeted peptide for molecular imaging of islet. We used phage display libraries to screen a beta-cell-targeted peptide, LNTPLKS, which was tagged with fluorescein isothiocyanate (FITC). This peptide was validated for targeting beta-cell with in vitro and in vivo studies. Immunocytochemistry (ICC) and fluorescence-activated cell sorting (FACS) analysis were used to validate the target specificity of the peptide. FITC-LNTPLKS displayed much higher fluorescence in beta cells vs. control cells in ICC. This discrimination was consistently observed using primary rodent islet. FACS analysis showed right shift of peak point in beta cells compared to control cells. The specific bind to in situ islet was verified by in vitro experiments using rodent and human pancreatic slices. The peptide also showed high affinity of islet grafts under the renal capsule. In the insulinoma animal model, we could find FITC-LNTPLKS accumulated specifically to the tumor, thus indicating a potential clinical application of molecular imaging of insulinoma. In conclusion, LNTPLKS showed a specific probe for beta-cells, which might be further utilized in targeted imaging/monitoring beta cells and theragnosis for beta-cells-related disease (diabetes, insulinoma, etc.).

A novel tool for visualization and detection of pancreatic neuroendocrine tumours. A 'fluorescent' world is calling for exploration?

AIM OF THE STUDY

Pancreatic neuroendocrine tumours (pNETs) are rare tumours with a propensity to metastasize. Physicians frequently face a huge clinical challenge during the localization of these lesions. The aim of this study is to investigate whether fluorescence-guided localization techniques with indocyanine green (ICG) can be utilized as a detection tool in pNETs, along with any other clinical implications of this technique.

MATERIAL AND METHODS

A thorough literature search in PubMed and Google Scholar, under the terms 'ICG OR Indocyanine OR Fluorescence AND Neuroendocrine' until 31 June 2021, regarding the utilization of indocyanine-fluorescence in localization of pancreatic neuroendocrine, was conducted by the authors, and the associated results are presented.

RESULTS

Indocyanine fluorescence imaging may facilitate the efforts of surgeons to identify occult pancreatic neuroendocrine lesions, assisting them in the identification of resection margins and delineation of the surgical anatomy when it is difficult to clarify.

CONCLUSIONS

Indocyanine-fluorescence imaging might play a pivotal role in pancreatic surgery in terms of localization for neuroendocrine tumours. However, further large-scale clinical studies are needed to assess the absolute indications and optimal use of this technique.

JNETS clinical practice guidelines for gastroenteropancreatic neuroendocrine neoplasms: diagnosis, treatment, and follow-up: a synopsis

Neuroendocrine neoplasms (NENs) are rare neoplasms that occur in various organs and present with diverse clinical manifestations. Pathological classification is important in the diagnosis of NENs. Treatment strategies must be selected according to the status of differentiation and malignancy by accurately determining whether the neoplasm is functioning or nonfunctioning, degree of disease progression, and presence of metastasis. The newly revised Clinical Practice Guidelines for Gastroenteropancreatic Neuroendocrine Neoplasms (GEP-NENs) comprises 5 chapters-diagnosis, pathology, surgical treatment, medical and multidisciplinary treatment, and multiple endocrine neoplasia type 1 (MEN1)/von Hippel-Lindau (VHL) disease-and includes 51 clinical questions and 19 columns. These guidelines aim to provide direction and practical clinical content for the management of GEP-NEN preferentially based on clinically useful reports. These revised guidelines also refer to the new concept of "neuroendocrine tumor" (NET) grade 3, which is based on the 2017 and 2019 WHO criteria; this includes health insurance coverage of somatostatin receptor scintigraphy for NEN, everolimus for lung and gastrointestinal NET, and lanreotide for GEP-NET. The guidelines also newly refer to the diagnosis, treatment, and surveillance of NEN associated with VHL disease and MEN1. The accuracy of these guidelines has been improved by examining and adopting new evidence obtained after the first edition was published.

A case report on a protracted course of a hidden insulinoma

Introduction

Insulinoma is a functioning pancreatic neuroendocrine tumor primarily leading due to hypoglycemia due to hypersecretion of insulin. This case illustrates the real challenges faced in the detection of an occult insulinoma, which resulted in a protracted course of the disease.

Case presentation

A 33-year-old female presented with recurrent hypoglycemia. Endogenous hyperinsulinemia was confirmed by a prolonged fast, however serial imaging was negative. Incidental finding of an ovarian mass gave rise to the suspicion of an insulin-producing ovarian tumor. Subsequent multimodality pancreatic imaging remained negative, requiring more invasive investigations. The tumor was localized by specialized arteriography using calcium stimulation to support the diagnosis of an insulinoma. However, repeated negative imaging led to further delays in definitive management, with worsening hypoglycemia. The surgery was finally performed three years after the initial presentation with successful removal of the tumor using intra-operative ultrasound.

Clinical discussion

It is important to emphasize that preoperative radiological imaging is useful to localize pancreatic lesions. However, most insulinomas could only be detected intraoperatively. The absence of suggestive radiological evidence should not deter surgeons from proceeding with definitive surgical intervention.

Conclusion

The case highlights the importance of a multidisciplinary approach in the management of a complicated case.

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Insulinoma is a difficult disease to diagnose due to its ambiguous location and insidious course.

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Insulinoma and type 2 diabetes mellitus coexistence is rare.

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Radiological imaging has improved in aiding the detection of pancreatic lesion but falsely negative results remain high.

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Surgical intervention is imperative for explorative diagnosis as well as treatment.

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A multidisciplinary approach could have been more successful in early detection and thus providing definitive treatment.

Insulinoma in pregnancy (a case presentation and systematic review of the literature)

Insulinomas are rare, benign and functional tumors that coincidentally may become overt during pregnancy or in the post-partum period. As the general symptoms of a pregnancy might cover the clinical presentation, diagnosing remains challenging. We present one additional case of a post-partum insulinoma, combined with a systematic review of the literature to sum up relevant details in diagnosis and treatment. A systematic request of Pubmed/Medline was conducted using the following terms: "insulinoma AND pregnancy" and "insulinoma" for a second request of ClinicalTrials.gov. All publications concerning pregnant or post-partum women with insulinoma were included. Thirty-six cases could be identified for analysis. Each publication was reviewed for demographic, diagnostic and therapeutic data. The most frequent clinical signs were unconsciousness and neurological symptoms. 64.9% were diagnosed during early pregnancy and 35.1% post-partum. 91.9% underwent surgery with a third resected during pregnancy without severe influence on fetal or maternal outcome. Three patients died of metastatic disease or misdiagnosing, two of them miscarried. Insulinoma in pregnancy is rare but should be considered in case of unclear hyperinsulinemic hypoglycemia. Surgery can be performed during the second trimester or post-partum with promising outcome.

Exendin-4-based imaging in endogenous hyperinsulinemic hypoglycaemia cohort: A tertiary Endocrine centre experience

CONTEXT

Insulinoma needs accurate preoperative localization for minimally invasive surgery. Exendin-4-based imaging has shown promising results.

OBJECTIVE

To evaluate performance parameters of exendin-4-based imaging in insulinoma localization and compare with other imaging modalities.

DESIGN

Retrospective cross-sectional study.

PATIENTS

We report 14 patients with endogenous hyperinsulinemic hypoglycaemia (EHH) managed at our centre; in whom, the final diagnosis was insulinoma (n = 11), Munchausen syndrome (MS) (n = 2) and inconclusive (n = 1). Retrospective reporting of CECT, ⁶⁸ Ga-DOTATATE PET/CT and ⁶⁸ Ga-NODAGA-exendin-4-PET/CT was done. With per-lesion analysis, performance parameters were calculated for the histopathological diagnosis of insulinoma.

MAIN OUTCOME MEASURES

True positive (TP), false positive (FP), false negative (FN), true negative (TN), sensitivity (Sn), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV) for insulinoma localization.

RESULTS

In our cohort, 12 histopathologically proven insulinoma lesions [(TP): 11 primary lesions, 1 metastasis] were detected in 11 patients, whereas two patients had MS (TN). Sn and PPV were 75% and 100%, 33.3% and 80% and 83.3% and 71.4% for CECT, ⁶⁸ Ga-DOTATATE PET/CT and ⁶⁸ Ga-NODAGA-exendin-4-PET/CT, respectively. With exendin-4-based imaging, FP uptake in normal pancreatic tissue and FN results in the pancreatic tail lesion was seen. In one patient, TN result suggested the correct diagnosis of MS.

CONCLUSION

⁶⁸ Ga-NODAGA-exendin-4-PET/CT has higher sensitivity than ⁶⁸ Ga-DOTATATE PET/CT and CECT for insulinoma localization. FP uptake in normal pancreas and FN result in tail lesions are limitations of currently utilized exendin-4-based imaging.

Seeking the unseen: Localization and surgery for an occult sporadic insulinoma

Insulinomas are rare pancreatic neuroendocrine tumours and the commonest cause for endogenous hyperinsulinaemic hypoglycemia. Small tumours are not easily detected by conventional cross-sectional imaging making localization prior to surgical removal a challenge. Selective arterial calcium stimulation is an invaluable adjunct to localization in such circumstances. This is further supplemented by intraoperative ultrasonography. A 39-year-old male was referred with features of Whipple’s triad of 10 months duration. Clinical and biochemical evaluation including C-peptide and serum insulin levels during supervised hypoglycemia concluded endogenous hyperinsulinaemia as the underlying aetiology. Contrast CT and MRI of the abdomen failed to localize the tumour. Selective arterial calcium stimulation localized the lesion in distal pancreas. During the surgery, tumour was further localized to the tail of the pancreas using intraoperative ultrasonography and enucleated. Histology confirmed an insulinoma and patient made an unremarkable recovery and was well more than a year after the surgery.

The functioning side of the pancreas: a review on insulinomas

PURPOSE

Insulinomas are a rare type of neuroendocrine tumors, originating in the pancreas, difficult to diagnose and to treat. Due to its rarity, insulinomas are a not well-known pathological entity; thus, the diagnostic process is frequently a medical challenge with many possible differential diagnoses. The diagnostic process varies between non-invasive procedures, such as the fasting test or imaging techniques, and invasive ones. Insulinomas are rarely malignant, but the glycemic imbalance correlated with this tumor can frequently alter the quality of life of the patients and the consequent hypoglycemia can be extremely dangerous. Moreover, insulinomas can be associated with different genetic syndromes, such as Multiple Endocrine Neoplasia 1, accompanied by other specific symptoms. There are many different treatment strategies, depending on the need to control symptoms or control diseases progression, the only curative one being surgery.

METHODS AND RESULTS

We reviewed the evidences present in the literature on insulinomas and reported its main clinical characteristics and management strategies.

CONCLUSION

The aim of this review of the literature is to present the current knowledge on insulinomas, exploring the main clinical characteristics, the diagnostic tools, and the therapeutic strategies.

Extrapancreatic insulinoma

A 38-year-old female presented with recurrent episodes of hypoglycemia for 5 years. On 72-h fast test, critical sample biochemistry was suggestive of endogenous hyperinsulinemic hypoglycemia. Both constrast-enhanced computed tomography and ⁶⁸Ga-DOTATATE positron emission tomography/computerized tomography (PET/CT) revealed no pancreatic lesion but showed a jejunal lesion suggestive of neuroendocrine tumor (NET) but not confirmatory of insulinoma. ⁶⁸Ga-Exendin-4 PET/CT showed intense uptake in the proximal jejunum, and this being a specific scan for insulinoma, confirmed it as an ectopic insulinoma. The patient attained normoglycemia after excision of this NET confirming it to be a case of ectopic insulinoma located in the jejunum. Although most insulinomas are located in the pancreas, rarely ectopic cases have been described in the spleen, perisplenic tissue, duodenohepatic ligament, adjacent to the ligament of Treitz, duodenum, and the jejunum. Functional scanning with ⁶⁸Ga-Exendin-4 PET/CT scan aids the localization of ectopic insulinoma.

Diagnostic value of ASVS for insulinoma localization: A systematic review and meta-analysis

BACKGROUND

Previous studies on the diagnostic value of arterial calcium stimulation with hepatic venous sampling (ASVS) for the localization of insulinoma have reported inconsistent results. Here, we performed a meta-analysis of the relevant published studies.

METHODS

PubMed, Embase, Web of Science, the Cochrane Library, and Wanfang Data were searched for studies on the diagnostic value of ASVS in insulinoma localization published up to May 2019. We calculated the sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and receiver operating characteristic (ROC) curve of ASVS in the localization of insulinoma.

RESULTS

We included ten studies involving 337 patients in the study. The pooled sensitivity, specificity, PLR, and NLR were 0.93 (95% confidence interval [CI]: 0.83-0.97), 0.86 (95%CI: 0.75-0.93), 6.8(95%CI: 3.7-12.7), and 0.08 (95%CI: 0.03-0.19), respectively. The DOR was 84 (95%CI: 30-233), and the area under the ROC curve was 0.96 (95%CI: 0.94-0.97).The results of the heterogeneity of the studies (P = 0.00, I2 = 80.17) were calculated using forest plots of the DOR.

CONCLUSION

ASVS is of significant value in localization of insulinoma. If a qualitative diagnosis of insulinoma is definite and the imaging examination results are negative, ASVS should be performed to confirm the localization of insulinoma.

Uncommon Manifestation of Hypoglycemia in a Patient with Insulinoma – A Case Report

Insulinoma are insulin-secreting tumors of pancreatic origin that generates hypoglycemia by excessive secretion of insulin. Insulinoma is a rare disease ant the most tumors are benign, solitary and occur at intrapancreatic sites.

Case report. A 42-year old Caucasian women was hospitalized at the “Prof. N.C. Paulescu” National Institute of Diabetes, Nutrition and Metabolic Diseases Bucharest in April 2019 after an episode of hypoglycaemia remitted after intravenous glucose administration. Patient accused for about two weeks anxiety phenomena. At the time of admission in the hospital the patient was conscious in a good general condition. Paraclinical investigations revealed basal blood glucose 29 mg/dl, fasting insulin serum 87.7 µU/ml and pancreatic C-peptide-7.90 ng/ml. During hospitalization under strict glycaemic monitoring, the patient presented frequent asymptomatic hypoglycemic episodes that was remitted after intravenous glucose administration. Nuclear magnetic resonance highlighted a nodular lesion of the pancreas and in May 2019 the tumor resection was practiced. After surgery the blood glucose ranged between 86 mg/dl and 116 mg/dl. To mention that patient has a family history of diabetes and she’s obese.

Conclusion. This case suggests that lack symptoms of hypoglycaemia may be present in patients with insulinoma. Diagnostic of insulinoma requires high clinical suspicions, accurate biochemical investigations and imaging techniques for the localization of the tumor and may represent a challenge in certain situations.

Rare malignant insulinoma with multiple liver metastases derived from ectopic pancreas: 3-year follow-up and literature review

Here, we report the diagnosis and treatment of a very rare case of malignant insulinoma derived from ectopic pancreas. A middle-aged woman presented with a 6-year history of recurrent hypoglycemia with multiple lesions in liver. Admission workup revealed elevated serum insulin and C-peptide, as well as multiple lesions in the liver (largest being 4.3 cm), enlarged lymph nodes around the pancreas, and a lesion (of 3.5 cm) at the proximal jejunum, as shown by contrast computed tomography (CT). Liver biopsy showed the lesions to be well-differentiated neuroendocrine tumors, grade G1. 68Gallium-exendin-4 positron emission tomography/CT confirmed the origin as the lesion located at the jejunum. The combination treatment of everolimus plus long-acting octreotide relieved symptoms and achieved a partial tumor response. Maintenance treatment of the somatostatin analog (ie, octreotide) alone was administered. Three years of follow-up, up to the writing of this report, showed good survival, with the patient remaining asymptomatic and euglycemic without disease progression. This case shows that 68Gallium-exendin-4 positron emission tomography/CT is useful for locating insulinoma, especially for insulinoma derived from ectopic pancreas, and that everolimus plus octreotide with maintenance somatostatin analog alone is an effective drug strategy for treating inoperable malignant insulinoma.

Association of Insulinoma and Type 2 Diabetes Mellitus

The association of diabetes mellitus and insulinoma is unusual. We are reporting the case of a 58 years old patient having diabetes mellitus type 2 for several years. This patient was well balanced with oral anti-diabetic treatment. However, the diagnosis of insulinoma was discussed due to recent episodes of hypoglycemia that persisted even after stopping the treatment. Abdominal CT allowed the topographic diagnosis. The patient underwent a caudal pancreatectomy. Furthermore, the postoperative period shows that the diabetes mellitus requires the oral anti-diabetic treatment and basal insulin have to be stable. Then, the occurrence of hypoglycemia in the diabetic mellitus type 2 and, especially the persistence after discontinuation of therapy, suggest the unusual diagnosis of insulinoma as illustrated in our observation.

Organic hyperinsulinism: radiological diagnostics and surgical treatment

AIM

To optimize the diagnosis and surgical treatment of insulinoma and nesidioblastosis.

MATERIAL AND METHODS

42 patients with organic hyperinsulinism (OH) were operated. There were 39 cases of insulinoma including 2 patients with insulinoma combined with nesidioblastosis and 3 cases of nesidioblastosis alone. Preoperative ray imaging consisted of percutaneous, endoscopic and intraoperative sonography, contrast-enhanced computed tomography, magnetic resonance imaging (MRI). Functional test included arterial-stimulated blood sampling (ASBS). Laparotomy and robot-assisted techniques were used in 22 and 20 patients.

RESULTS

Sensitivity was 62.0%, 76.9%, 83.3%, 87.5%, 94.8% and 100% in percutaneous sonography, CT, endoscopic sonography, MRI, intraoperative sonography and ASBS respectively. Postoperative complications were observed in 14 and 6 patients after conventional and robot-assisted surgery. 2 patients died. Overall mortality was 4.8%. None patient had recurrent hypoglycemic conditions in long-term postoperative period (mean follow-up 18.7 months).

CONCLUSIONS

Comprehensive survey allowed to define the cause of OH. Minimally invasive organ-sparing surgery has satisfactory immediate and remote results in these patients.

Identification of CD90 as Putative Cancer Stem Cell Marker and Therapeutic Target in Insulinomas

The long-term prognosis after surgical resection of malignant insulinoma (INS) is poor. Novel adjuvant therapies, specifically targeting cancer stem cells (CSCs), are warranted. Therefore, the goal of this study was to characterize and target putative INS CSCs. Using fluorescence-activated cell sorting, human INS cell line CM and pancreatic carcinoid cell line BON1 were screened for the presence of stem cell-associated markers. CD90, CD166, and GD2 were identified as potential CSC markers. Only CD90(+) INS cells had an increased tumor-initiating potential in athymic nude mice. Anti-CD90 monoclonal antibodies decreased the viability and metastatic potential of injected cells in a zebrafish embryo INS xenograft model. Primary INS stained positive for CD90 by immunohistochemistry, however also intratumoral fibroblasts and vascular endothelium showed positive staining. The results of this study suggest that anti-CD90 monoclonals form a potential novel adjuvant therapeutic modality by targeting either INS cells directly, or by targeting the INS microenvironment.

Arterial Calcium Stimulation with Hepatic Venous Sampling in the Localization Diagnosis of Endogenous Hyperinsulinism

Objective. The aim of this study was to assess the utility of arterial calcium stimulation with hepatic venous sampling (ASVS) in the localization diagnosis of endogenous hyperinsulinism. Patients and Methods. A retrospective descriptive study was performed including patients with endogenous hyperinsulinism who underwent ASVS. The histopathological diagnosis in patients who underwent a surgical procedure was used as the reference for the statistical study of the accuracy of this technique. Results. 30 patients were included with endogenous hyperinsulinism and nonconclusive imaging diagnosis was included. ASVS was performed in all cases. Surgery was performed in 20 cases. Insulinoma was removed in 19 patients; the location of all cases was detected in the ASVS. All cases of endogenous hyperinsulinism had a positive result for the ASVS, with this association being statistically significant (χ² = 15.771; p < 0.001). A good and statistically significant agreement was obtained between histopathologic diagnosis and ASVS results (K = 0.518, p < 0.001). Conclusions. ASVS is a useful procedure in the localization diagnosis of endogenous hyperinsulinism undetected by other imaging tests. This technique allows the localization of intrapancreatic insulinomas and represents useful tool for the diagnosis and surgical management of these tumors.

Long-standing insulinoma: two case reports and review of the literature

Background

Insulinomas are rare pancreatic endocrine tumors. Most are benign and solitary. However, the nonspecific symptoms and small size of these tumors led to difficulties of diagnosis and localization.

Case presentation

We present two Arab patients with pancreatic long-standing insulinoma. Both patients presented episodic hypoglycemic symptoms respectively during 10 and 2 years. Biochemical and morphological workup detected localized pancreatic insulinoma. Open procedure surgery was done for the two patients and insulinomas were successfully removed by enucleation.

Conclusion

Insulinoma remains a diagnostic challenge to practitioners. Diagnosis of suspected cases is easily confirmed by standard endocrine tests, especially the supervised fasting test. Accurate preoperative localization is essential for more effective and safest surgery.

Severe Unresponsive Hypoglycemia Associated with Neuroendocrine Tumor of Unknown Primary Site - 18 Years after Rectal Cancer Surgery. Case Report

INTRODUCTION

Neuroendocrine tumors are derived from cells that have the unique ability to synthesize, store and secrete a variety of metabolically active substances, peptides and amines, characteristic of the tissue of origin, which can cause distinct clinical syndromes.

MATERIAL AND METHODS

We present the case of a 58-year-old patient diagnosed and surgically treated in January 1996 for stage III inferior rectal cancer, who was readmitted after 18 years presenting persistent diarrheic syndrome and asthenia. Investigations performed (abdominal CT) showed multiple liver metastases, initially suspected as being related to the rectal cancer. Biopsy of liver metastases and pathological and immunohistochemical analysis demonstrated the neuroendocrine origin (moderately differentiated neuroendocrine tumor). Seven months after the identification of liver metastases and after initiation of oncological therapy with Interferon and Somatostatin, the patient presented severe hypoglycemia (serum glucose 13-70 mg/dl) proved to be due to insulin-like factors (serum insulin level 64.9 ìU/ml) secreted by metastases. Due to the aggressive evolution of neuroendocrine tumor, with multiple episodes of severe hypoglycemia, resistant to treatment, the patient died approximately one month after the occurrence of hypoglycemic episodes.

CONCLUSION

Despite comprehensive tests (abdominal CT scan, colonoscopy, bone scintigraphy and PET/CT), the primary site of the neuroendocrine tumors remained unknown.

Impact of variant pancreatic arterial anatomy and overlap in regional perfusion on the interpretation of selective arterial calcium stimulation with hepatic venous sampling for preoperative localization of occult insulinoma

BACKGROUND

To determine the impact of variant pancreatic arterial anatomy and overlap in regional perfusion on the interpretation of selective arterial calcium stimulation (SACST) with hepatic venous sampling for preoperative localization of occult insulinoma.

METHODS

An institutional review board-approved retrospective review was undertaken of 42 patients with surgically confirmed, occult insulinoma who underwent SACST from January 1996 to March 2014. Location of the insulinoma was predicted initially based on the biochemical results of SACST alone according to Doppman's criteria. Pancreatic arteriograms were reviewed blinded to the biochemical results and the regional perfusion of each artery assessed. The anatomic and perfusion data were combined with the biochemical results to make a second prediction and compared with the surgical findings.

RESULTS

The biochemical results were positive in 1, 2, and 3 arterial distributions in 73.8%, 21.4%, and 4.8% of patients, respectively. The celiac trunk and superior mesenteric artery (SMA) anatomy were aberrant in 38.1% and 35.7% of patients, respectively. Clinically significant variations included dorsal pancreatic artery replaced to SMA (21.4%) and celiac stenosis (4.8%). Significant variation and overlap in regional pancreatic perfusion was observed, particularly for the SMA. Sensitivity for insulinoma localization was 54.8% (diagnostic arteriography), 73.8% (biochemical data), 88.1% (biochemical, anatomic, perfusion data), and 92.8% (arteriographic, biochemical, anatomic, perfusion data).

CONCLUSION

Careful review of the pancreatic arterial anatomy and regional perfusion is critical for correct interpretation of the biochemical results of SACST and improves the sensitivity of localization for occult insulinoma, particularly in the presence of pancreatic arterial variants or overlap in regional perfusion.

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.

Management of endocrine disease: a clinical update on tumor-induced hypoglycemia

Tumor-induced hypoglycemia (TIH) is a rare clinical entity that may occur in patients with diverse kinds of tumor lineages and that may be caused by different mechanisms. These pathogenic mechanisms include the eutopic insulin secretion by a pancreatic islet β-cell tumor, and also the ectopic tumor insulin secretion by non-islet-cell tumor, such as bronchial carcinoids and gastrointestinal stromal tumors. Insulinoma is, by far, the most common tumor associated with clinical and biochemical hypoglycemia. Insulinomas are usually single, small, sporadic, and intrapancreatic benign tumors. Only 5-10% of insulinomas are malignant. Insulinoma may be associated with the multiple endocrine neoplasia type 1 in 4-6% of patients. Medical therapy with diazoxide or somatostatin analogs has been used to control hypoglycemic symptoms in patients with insulinoma, but only surgical excision by enucleation or partial pancreatectomy is curative. Other mechanisms that may, more uncommonly, account for tumor-associated hypoglycemia without excess insulin secretion are the tumor secretion of peptides capable of causing glucose consumption by different mechanisms. These are the cases of tumors producing IGF2 precursors, IGF1, somatostatin, and glucagon-like peptide 1. Tumor autoimmune hypoglycemia occurs due to the production of insulin by tumor cells or insulin receptor autoantibodies. Lastly, massive tumor burden with glucose consumption, massive tumor liver infiltration, and pituitary or adrenal glands destruction by tumor are other mechanisms for TIH in cases of large and aggressive neoplasias.

Insulinoma: rare yet important

We report our experience with six cases of insulinoma that were managed at our hospital between 2009 and 2013. Four patients were women and two men, with mean age of 43 years and mean duration of symptoms before diagnosis of 5.7 years. Biochemical confirmation was made in all cases and preoperative localisation was successful in two cases only. In the other four, intraoperative localisation was made. Enucleation was performed in four patients and distal pancreatectomy in the other two. The tumour was proved benign in all patients by histopathology. Postoperatively, all patients were asymptomatic during a follow-up period ranging from 9 months to 4 years and both serum glucose and insulin were normal during that period. We think that careful preoperative workup and skilful surgical techniques can end the prolonged suffering of patients with insulinomas with excellent results.

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.

Is laparoscopic approach for pancreatic insulinomas safe? Results of a systematic review and meta-analysis

BACKGROUND

No consensus exists as to whether laparoscopic treatment for pancreatic insulinomas (PIs) is safe and feasible. The aim of this meta-analysis was to assess the feasibility, safety, and potential benefits of laparoscopic approach (LA) for PIs. The abovementioned approach is also compared with open surgery.

METHODS

A systematic literature search (MEDLINE, EMBASE, Cochrane Library, Science Citation Index, and Ovid journals) was performed to identify relevant articles. Articles that compare the use of LA and open approach to treat PI published on or before April 30, 2013, were included in the meta-analysis. The evaluated end points were operative outcomes, postoperative recovery, and postoperative complications.

RESULTS

Seven observational clinical studies that recruited a total of 452 patients were included. The rates of conversion from LA to open surgery ranged from 0%-41.3%. The meta-analysis revealed that LA for PIs is associated with reduced length of hospital stay (weighted mean difference, -5.64; 95% confidence interval [CI], -7.11 to -4.16; P < 0.00001). No significant difference was observed between LA and open surgery in terms of operation time (weighted mean difference, 2.57; 95% CI, -10.91 to 16.05; P = 0.71), postoperative mortality, overall morbidity (odds ratio [OR], 0.64; 95% CI, 0.35-1.17; P = 0.14], incidence of pancreatic fistula (OR, 0.86; 95% CI, 0.51-1.44; P = 0.56), and recurrence of hyperglycemia (OR, 1.81; 95% CI, 0.41-7.95; P = 0.43).

CONCLUSIONS

Laparoscopic treatment for PIs is a safe and feasible approach associated with reduction in length of hospital stay and comparable rates of postoperative complications in relation with open surgery.

The role of exendin-4-conjugated superparamagnetic iron oxide nanoparticles in beta-cell-targeted MRI

Noninvasive targeted visualization of pancreatic beta cells or islets is becoming the focus of molecular imaging application in diabetes and islet transplantation studies, but it is currently unsuccessful due to the lack of specific beta cell biomarkers. Glucagon-like peptide 1 receptor (GLP-1R) is highly expressed in beta cells and considered as a promising target. We here developed a targeted superparamagnetic iron oxide (SPIO) nanoparticle using GLP-1 analog-exendin-4 which is conjugated to polyethylene glycol coated SPIO (PEG-SPIO). The results demonstrated that exendin-4 functionalized SPIO was able to specifically bind to and internalized by GLP-1R-expressing INS-1 cells, with the higher labeling efficiency than non-targeted nanoparticles. Notably, SPIO-exendin4 could differentially label islets in pancreatic slices or beta cell grafts in vitro. Systemic delivery of SPIO-exendin4 into nude mice bearing s.c. insulinomas (derived from INS-1 cells) leads to the accumulation of the nanoparticles in tumors, generating a strong magnetic resonance imaging contrast detectable by a clinical MRI scanner at field strength of 3.0 T, and the iron deposition in tumors was further confirmed by Prussian blue staining. Furthermore, preliminary biodistribution study indicated that SPIO-exendin4 had a tendency to accumulate in pancreas. Toxicity assessments demonstrated good biocompatibility in vivo. These results suggest that SPIO-exendin4 has potential as molecularly targeted imaging agents for in vivo imaging of insulinoma, and possibly for future beta cell imaging.

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.

Metabolic acidosis as a complication of intravenous dextrose administration in a patient with insulinoma

There are few cases published in literature in which the use of intravenous dextrose as treatment for an insulinoma resulted in a metabolic acidosis. This is due perhaps to the usual method of administration, which is usually at low concentrations, for limited periods or low volumes. We present the case of a woman with suspected insulinoma by laboratory findings in which an endogenous hyperinsulinism was observed. During hospitalization, the patient required a progressive increase of the glucose infusion to prevent severe hypoglycemia. Two days before surgery, the patient presented symptoms of malaise and muscle weakness and a metabolic acidosis with hypokalemia became apparent in the blood analysis. This metabolic imbalance was attributed to a long period of treatment with high volume of intravenous dextrose infusion. If large doses of dextrose are required in a patient with an insulinoma, then the possibility of a metabolic imbalance must be considered during the follow-up. When the suspicion of an insulinoma is high, and all the attempts of pre-operative localization fail, patients should be derived early to specialized centers with modern imaging techniques, so that surgery is not delayed, and this rare and threatening complication could be avoided.

Clinical profile of insulinoma: analysis from a tertiary care referral center in India

OBJECTIVE

To describe the clinical presentation, localization techniques, surgical procedures and outcome in patients with insulinoma.

METHODS

Retrospective analysis of case records of patients diagnosed with insulinoma between January 1993 and June 2009 at a tertiary-care hospital was done. Seventeen patients underwent diagnostic 72-h fast. The sensitivity of computed tomography (CT) of pancreas was judged using intraoperative findings as the gold standard.

RESULTS

Twenty-six patients (19 women) with mean age 42.2 years (median age 39.5 years) with biochemical/imaging evidence of insulinoma were included. All patients who underwent 72-h fast developed symptomatic hypoglycemia within 48 h. The sensitivity and positive predictive value (PPV) of CT of pancreas was 68.4% and 92.8%, respectively. Twenty patients underwent surgery, of whom four were operated on without preoperative localization. Four patients had recurrence of symptoms. Of the six patients who were not operated upon, the lesion was localized in four.

CONCLUSION

This audit shows that all patients with insulinoma develop hypoglycemia within 48 h of fasting. CT of pancreas localizes the lesion in two thirds of cases and would be a useful initial investigation in patients with suspected insulinoma.

A case of occult insulinoma localized by pancreatic dynamic enhanced spiral CT

Insulinomas are the most common category of pancreatic endocrine tumors, with an annual incidence of 1-4 cases per million people. Most are intrapancreatic, benign and solitary. Therefore, they have an excellent prognosis after surgical resection. However, the localization diagnosis of insulinomas still poses a challenge to surgeons and radiologists. In this case, the tumor was occult and could not be found by either abdominal enhanced spiral computed tomography (CT) or ultrasonography. Therefore, we tried a new method of CT scanning and localized the tumor.

[Usefulness of arterial calcium stimulation with hepatic venous sampling in the localization diagnosis of endogenous hyperinsulinism]

BACKGROUND AND OBJECTIVE

The aim of this study was to assess the utility of arterial calcium stimulation with hepatic venous sampling (ASVS) in the localization of tumors in patients with endogenous hyperinsulinism not detected with other methods.

PATIENTS AND METHODS

We performed a retrospective study of 26 patients admitted to our hospital for hypoglycemia who underwent ASVS because the source of hyperinsulinism was not clearly identified by other imaging techniques. The histopathological result in patients who underwent a surgical procedure was considered the reference for statistical study of the accuracy of this technique. Statistical analysis was performed by comparing proportions with the chi-squared test with Yates' correction for contingency tables, and Cohen's kappa coefficient as a measure of interrater agreement between two observations.

RESULTS

Surgery was performed in 17 patients, 13 with positive ASVS and the remaining four with negative results. An insulinoma was removed in 12 patients, and 10 of these were detected in the ASVS. A total of 76.9 % of positive ASVS tests corresponded to a histological diagnosis of insulinoma, and 83% of these insulinomas were positive in ASVS. This association was statistically significant (chi cuadrado=7.340; p=0.012). Two of three patients with nesidioblastosis had a positive response in the ASVS. A good and statistically significant agreement was obtained between histopathologic diagnosis and ASVS results (kappa=0.556, p = 0.007).

CONCLUSIONS

ASVS is a useful procedure in the localization diagnosis of endogenous hyperinsulinism not detected by other imaging tests. This technique allows tumors in the pancreatic gland to be identified and may be useful in the choice of the surgical technique to be used.

68Ga-labelled exendin-3, a new agent for the detection of insulinomas with PET

Purpose

Insulinomas are neuroendocrine tumours derived from pancreatic β-cells. The glucagon-like peptide 1 receptor (GLP-1R) is expressed with a high incidence (>90%) and high density in insulinomas. Glucagon-like peptide 1 (GLP-1), the natural ligand of GLP-1R, is rapidly degraded in vivo. A more stable agonist of GLP-1R is exendin-3. We investigated imaging of insulinomas with DOTA-conjugated exendin-3 labelled with ⁶⁸Ga.

Methods

Targeting of insulinomas with [Lys⁴⁰(DOTA)]exendin-3 labelled with either ¹¹¹In or ⁶⁸Ga was investigated in vitro using insulinoma tumour cells (INS-1). [Lys⁴⁰(¹¹¹In-DTPA)]Exendin-3 was used as a reference in this study. In vivo targeting was investigated in BALB/c nude mice with subcutaneous INS-1 tumours. PET imaging was performed using a preclinical PET/CT scanner.

Results

In vitro exendin-3 specifically bound and was internalized by GLP-1R-positive cells. In BALB/c nude mice with subcutaneous INS-1 tumours a high uptake of [Lys⁴⁰(¹¹¹In-DTPA)]exendin-3 in the tumour was observed (33.5 ± 11.6%ID/g at 4 h after injection). Uptake was specific, as determined by coinjection of an excess of unlabelled [Lys⁴⁰]exendin-3 (1.8 ± 0.1%ID/g). The pancreas also exhibited high and specific uptake (11.3 ± 1.0%ID/g). High uptake was also found in the kidneys (144 ± 24%ID/g) and this uptake was not receptor-mediated. In this murine tumour model optimal targeting of the GLP-1R expressing tumour was obtained at exendin doses ≤0.1 µg. Remarkably, tumour uptake of ⁶⁸Ga-labelled [Lys⁴⁰(DOTA)]exendin-3 was lower (8.9 ± 3.1%ID/g) than tumour uptake of ¹¹¹In-labelled [Lys⁴⁰(DTPA)]exendin-3 (25.4 ± 7.2%ID/g). The subcutaneous tumours were clearly visualized by small-animal PET imaging after injection of 3 MBq of [Lys⁴⁰(⁶⁸Ga-DOTA)]exendin-3.

Conclusion

[Lys⁴⁰(⁶⁸Ga-DOTA)]Exendin-3 specifically accumulates in insulinomas, although the uptake is lower than that of [Lys⁴⁰(¹¹¹In-DTPA)]exendin-3. Therefore, [Lys⁴⁰(⁶⁸Ga-DOTA)]exendin-3 is a promising tracer to visualize insulinomas with PET.

[Hypoglycemia and insulinoma]

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

The usefulness of super-selective computed tomography angiography (CTA) for diagnosing and localizing a small insulinoma

Localization of insulinomas by preoperative imaging is critical for successful surgical resection. However, the visualization and localization of small insulinomas by recent imaging modalities still remains a challenge. Here, we report a 77-year-old woman with a small insulinoma successfully localized by performing arterial stimulation and venous sampling (ASVS), and subsequent super-selective CTA (SSCTA). It was not visualized by routine non-invasive imaging tests such as digital subtraction angiography (DSA). The small size (1.0 cm) of the surgically removed tumor supports the usefulness of SSCTA for localizing very small insulinomas.

Intraoperative localization of insulinoma and normal pancreas using invisible near-infrared fluorescent light

BACKGROUND

Neuroendocrine tumors of the pancreas, such as insulinoma, are difficult to localize, and complete resection is essential for cure. Our hypothesis is that a near-infrared (NIR) fluorophore exhibiting uptake in insulinoma could provide high-sensitivity detection intraoperatively.

MATERIALS AND METHODS

The optical properties of methylene blue (MB) were measured in vitro in 100% serum at 37 degrees C and in vivo after tissue uptake. MB was injected as a rapid intravenous bolus at doses ranging from 0.25 to 2 mg/kg into wildtype rats and pigs, and into insulinoma-bearing transgenic mice. The FLARE imaging system was used to acquire color video and NIR fluorescence images simultaneously and in real-time. The signal-to-background ratios (SBR) of tissues and tumors were quantified using FLARE software.

RESULTS

When appropriately diluted, MB exhibits moderate NIR fluorescence emission peaking at 688 nm. At doses > or =1 mg/kg, certain normal tissues, such as pancreas, accumulate MB and remain NIR fluorescent for up to 1 h with an SBR > or = 1.6. MB spectral properties are maintained after uptake into tissue. Interestingly, insulinoma exhibits even higher MB signal than normal pancreas, resulting in insulinoma-to-pancreas ratios of 3.7 and insulinoma-to-muscle ratios of 16.2. MB permitted high-sensitivity, real-time localization of primary, multicentric, and metastatic insulinoma and permitted differentiation among tumor, normal pancreas, and other abdominal structures.

CONCLUSION

A single intravenous injection of a clinically available, commonly used NIR fluorophore provides prolonged intraoperative localization of normal pancreas and insulinoma using invisible NIR fluorescent light.

What should be done in an operating room when an insulinoma cannot be found?

Insulinoma is the most common (functioning) islet cell tumour of the pancreas and is highly curable with accurate localization and precise extirpation of the often benign, solitary lesion. Although previous reports describe high success rates without pre-operative localization, more recent recognition of the overlap among causes of endogenous hyperinsulinism, coupled with the deleterious long-term effects of blind distal pancreatectomy and re-operation, mandate the need for precise pre-operative localization or regionalization of the tumour(s). If these criteria have not been met and the surgeon finds him/herself in the operating room without a localized or regionalized tumour, the operation should be concluded without resection, the diagnosis reconfirmed, and a calcium stimulation test performed. At experienced centres, this can be often carried out within 24-48 h and the patient returned to the operating room for a gradient-guided resection. Intraoperative venous sampling for insulin might be an option in the future but its accuracy has not been validated in sufficient numbers of patients to date.

[Giant insulinoma]

Islet-cell tumors are the most common neuroendocrine tumors that arise from the endocrine pancreas. They are typically benign and sporadic. Diagnosis is generally established late because clinical signs lack specificity. The insulinoma is difficult to localize since it is very small in size, often not exceeding 2cm. We report an exceptional case of giant insulinoma initially revealed by a pseudo-polycythemia in an 80-year-old man. He had been treated for hypertension for a few months. Routine biological investigations showed elevated hematocrit and haemoglobin, suggesting Vaquez disease. History taking revealed recent episodes of nocturnal agitation. On admission, he had reddish skin with a suspected enlarged spleen, but total blood volume was normal. Imaging studies showed a voluminous tumor located between the pancreas and the spleen. The presence of an insulinoma was confirmed on the basis of an elevated level of proinsulin at the time of an asymptomatic episode of hypoglycemia. Spleno-pancreatectomy was performed. Histopathological examination revealed a malignant, well-differentiated neuroendocrine malignant tumor.

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.