Evaluation of preoperative and intraoperative arterial stimulation and venous sampling for diagnosis and surgical resection of insulinoma

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.

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.

Hypoglycaemia in an adult male: a surprising finding in pursuit of insulinoma

A 50-year-old man who had suffered several episodes of early morning sweats and tremors was diagnosed as having hyperinsulinaemic hypoglycaemia. Cross-sectional imaging and endoscopic ultrasound revealed no pancreatic lesion. A selective intra-arterial calcium infusion study showed a two-fold increase of insulin secretion after infusion of the splenic and superior mesenteric arteries. Laparotomy was performed, no lesion was identified after full mobilisation of the pancreas, and nothing was evident with intra-operative ultrasound. A distal pancreatectomy was performed. Microscopically, the pancreas exhibited diffuse islet cell hyperplasia consistent with nesidioblastosis. The patient remains euglycaemic eight months post-operatively.

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.

Laparoscopic surgery in patients with sporadic and multiple insulinomas associated with multiple endocrine neoplasia type 1

There have recently been reports of a limited number of laparoscopic procedures in patients with clinically manifest hyperinsulinism. However, the precise role of laparoscopy remains unknown. Between January 1998 and September 2003, 11 consecutive patients (10 women and 1 man; mean age, 40 years; age range, 22-66 years) with sporadic insulinoma and two female patients (25 and 40 years old) with multiple insulinomas associated with multiple endocrine neoplasia type 1 (MEN-1) were operated on using the laparoscopic approach. Endoscopic ultrasonography was used to localize the tumor preoperatively in 90% of patients with sporadic insulinoma. In patients with MEN-1, computed tomography and octreoscan-(111)In demonstrated multiple tumors. Laparoscopic ultrasonography (LapUS) was performed in all patients for operative decision-making. Of 11 patients with sporadic insulinoma, laparoscopic enucleation (LapEn) was planned in 8 patients, but in 1 patient, the use of LapUS missed the tumor and the patient was converted to open surgery. Mean operating time after LapEn (seven patients) was 180 minutes, and the mean blood loss was 200 ml. The mean hospital stay was 5 days. In three of the 11 patients, laparoscopic spleen-preserving distal pancreatectomy (LapSPDP) was performed; the mean operative time was 240 minutes, and the mean blood loss was 360 ml. Postoperative complications occurred in three of seven patients after LapEn (three pancreatic fistulas managed conservatively, and one case of bleeding requiring reoperation). LapSPDP was performed in both patients with MEN-1; in one patient with splenic vessel preservation (SVP), the operating time was 210 minutes and blood loss was 650 ml, with a hospital stay of 6 days. In another patient without SVP, the operating time was 150 minutes and blood loss was 300 ml. The latter patient developed a 4-cm splenic infarct managed conservatively, and the hospital stay was 14 days. LapEn and LapSPDP are feasible and safe and achieved cure in patients with sporadic insulinoma and multiple insulinomas associated with MEN-1. However, the risk of pancreatic leakage after LapEn remains high, and LapSPDP without SVP may be associated with splenic infarct.

Nesidioblastosis associated with hyperinsulinemic hypoglycemia in adults: review of the literature

Nesidioblastosis is a term that was first introduced by Laidlaw in 1938 to define the diffuse proliferation of pancreatic islet cells budding from ductal epithelium. First described in neonates, it is widely recognized to be the primary cause of persistent hyperinsulinemic hypoglycemia in infants. In adults, insulinoma accounts for most cases of hyperinsulinemic hypoglycemia. Adult-onset nesidioblastosis associated with hyperinsulinemic hypoglycemia is a very rare entity, representing 0.5-5% of cases of organic hyperinsulinemia. Since 1981, when Harness et al. reported the first series of adult nesidioblastosis causing hypoglycemia, only 71 cases have been published. This article provides a guide for the diagnosis of organic hyperinsulinism and indicates when nesidioblastosis should be suspected. New diagnostic methods and treatment options for this rare disease are proposed. We also present a review of all reported cases of adult nesidioblastosis in the last 22 years.

Neuroendocrine Tumors of the Pancreas

Neuroendocrine tumors (NETs) are rare tumors of the endocrine pancreas that require a high degree of suspicion for timely diagnosis. Diagnosis is often delayed due to the nonspecific and intermittent presentation of symptoms. As many as 45% to 55% of tumors are nonfunctional and are typically diagnosed secondary to mass effect related symptoms or found incidentally. Functional tumors often are symptom specific and are diagnosed at an earlier stage than nonfunctional tumors. The challenging aspects of treating NETs are localizing the tumors, treating extensive or metastatic disease, and palliating symptoms. Most NETs have an indolent course, and aggressive multimodality treatment is often indicated and encouraged.

Metastatic insulinoma: case report and review of the literature

A 64-year-old nondiabetic woman presented with spells of lightheadedness and diaphoresis associated with lethargy and hunger of 2 weeks' duration. Physical examination was unremarkable; however, her fasting plasma glucose was 66 mg/dl, with concurrent plasma insulin of 171 microIU/ml (normal, 5-27 microIU/ml). Her C-peptide and pro-insulin levels were elevated, with negative insulin antibody and negative urinary sulfonylurea levels. Abdominal computed tomographic scan demonstrated a 5 x 4-cm mass in the tail of the pancreas and many liver metastases. She underwent resection of the pancreatic mass, radiofrequency ablation, and cauterization of hepatic lesions. Histology confirmed pancreatic insulinoma. Ten months later, she was free of hypoglycemic symptoms, with normal plasma insulin C-peptide and significantly decreased proinsulin levels. Insulinomas are rare, predominantly benign tumors. Surgery is the only curative treatment. Octreotide can be used to control hormone secretion and tumor growth. Other treatments include hepatic embolization, radiotherapy, chemotherapy, and liver transplantation.

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.

Rapid insulin assay for intraoperative confirmation of complete resection of insulinomas

BACKGROUND

Solitary insulinomas are usually the cause of organic hypoglycemia, whereas 13% to 24% of patients with hyperinsulinemia have multiple tumors or nesidioblastosis. Intraoperative glucose levels confirming complete excision have variable accuracy. Intraoperative insulin levels have been shown to predict operative outcome. The purpose of this study was to establish criteria for predicting operative success by using a new, rapid insulin assay as an intraoperative adjunct.

METHODS

Eight consecutive patients with organic hypoglycemia underwent pancreatic exploration. With an 8-minute immunochemiluminescent insulin assay, peripheral blood levels were obtained preoperatively, during resection, and at 5-minute intervals after surgical excisions. Operative findings and outcome were compared with intraoperative insulin/glucose ratios (I/G), glucose, and insulin levels.

RESULTS

By using the return of insulin levels to normal range and I/G ratios < or = 0.4 15 minutes after tumor(s) resection as criteria to predict operative success, 6 patients had their outcomes correctly predicted (5 true-positive and 1 true-negative). One patient with nesidioblastosis had a false-negative result. One could not be evaluated because of diazoxide medication. These criteria predicted postoperative absence of hypoglycemia with specificity of 100% and accuracy of 89%.

CONCLUSIONS

These 8-minute insulin assay and criteria can be a useful adjunct for intraoperative assurance of complete insulinoma resection and prediction of postoperative outcome.

A successful monitoring for intraoperative calcium stimulation test in complete resection of pancreatic insulinoma

IMPLICATIONS

An intraoperative arterial stimulation, venous sampling method was recently used for resection of insulinoma. In using this technique, some anesthetic concerns complicate the usual management of insulinoma. We suggest methods for solving these problems.

Islet cell tumors of the pancreas: the medical oncologist's perspective

Islet cell tumors of the pancreas are rare, indolent, neuroendocrine tumors. Approximately 50% of the patients diagnosed with these tumors present with symptoms related to various biologically active hormones that are secreted by these neoplasms. Currently, the only curative treatment for islet cell tumors is complete surgical resection. Management of metastatic disease is conservative. Initial treatment of these tumors includes expectant observation and medical management of symptoms with clinical monitoring and serial CT scans to assess tumor growth. Patients with rapidly progressive disease, with local symptoms caused by tumor bulk, or with uncontrolled symptoms related to hormone secretion require more aggressive medical or surgical intervention. The somatostatin analogue octreotide may help control hormone secretion and stabilize tumor growth. Patients refractory to octreotide with tumor predominantly in the liver are potential candidates for mechanical ablative techniques, such as hepatic arterial embolization. Radiofrequency ablation and cryosurgical techniques may also be useful, although specific data are limited. Surgical resection of metastatic disease may offer palliative relief of symptoms related to hormone secretion in carefully selected patients. Chemotherapy may be used for palliation when ablative techniques have failed or when significant extrahepatic disease is present. Streptozicin-based combinations remain the first line standard, but major objective responses are less common than had been previously thought. Because of the overall modest success of current chemotherapeutic regimens, patients with advanced disease in need of treatment should be encouraged to enroll in clinical trials testing newer antineoplastic agents or newer treatment strategies.