The importance of preoperative localisation procedures in organic hyperinsulinism--experience in 67 patients

Diffuse, Adult-Onset Nesidioblastosis/Non-Insulinoma Pancreatogenous Hypoglycemia Syndrome (NIPHS): Review of the Literature of a Rare Cause of Hyperinsulinemic Hypoglycemia

Differential diagnosis of hypoglycemia in the non-diabetic adult patient is complex and comprises various diseases, including endogenous hyperinsulinism caused by functional β-cell disorders. The latter is also designated as nesidioblastosis or non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS). Clinically, this rare disease presents with unspecific adrenergic and neuroglycopenic symptoms and is, therefore, often overlooked. A combination of careful clinical assessment, oral glucose tolerance testing, 72 h fasting, sectional and functional imaging, and invasive insulin measurements can lead to the correct diagnosis. Due to a lack of a pathophysiological understanding of the condition, conservative treatment options are limited and mostly ineffective. Therefore, nearly all patients currently undergo surgical resection of parts or the entire pancreas. Consequently, apart from faster diagnosis, more elaborate and less invasive treatment options are needed to relieve the patients from the dangerous and devastating symptoms. Based on a case of a 23-year-old man presenting with this disease in our department, we performed an extensive review of the medical literature dealing with this condition and herein presented a comprehensive discussion of this interesting disease, including all aspects from epidemiology to therapy.

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.

Is endoscopic ultrasonography more sensitive than magnetic resonance imaging in detecting and localizing pancreatic neuroendocrine tumors?

To compare endoscopic ultrasonography (EUS) and magnetic resonance imaging (MRI) in terms of their sensitivities to localize pancreatic neuroendocrine tumors (pNET) preoperatively. Systematic analysis of the literature; sensitivity of EUS and MRI in insulinomas and pancreaticoduodenal NETs in multiple endocrine neoplasia type 1 (MEN1) in series of at least 20 subjects referring to tumors confirmed by surgery and histopathology. Other imaging methods reported were also assessed. Eighteen publications on insulinomas (782 cases) could be analyzed, no study in MEN1 fulfilled the inclusion criteria and compared EUS to MRI. Data quality was moderate: all publications referred to case series. Mean correct detection / localization rates (sensitivity) were calculated: EUS 80%, MRI 66%, computed tomography 63%, angiography 52%, somatostatin receptor scintigraphy 42%, ultrasonography 23%; arterial calcium stimulation with hepatic venous sampling regionalized correctly in 80%. EUS seems to be more sensitive than MRI in localizing pancreatic neuroendocrine tumors. If a specialized endosonographist is available, EUS is the preferable imaging procedure. Otherwise, MRI is a suitable alternative.

Preoperative imaging and pathologic classification for pancreatic neuroendocrine tumors

The management of patients with pancreatic neuroendocrine tumor (PNET), whether hormonally secretory or not, is multidisciplinary and often multimodal. Surgical treatment plays a central role because complete resection is the only potentially curative treatment. The choice of the therapeutic plan for a PNET requires precise localization of the primary tumor (which may sometimes be multiple in case of genetic predisposition), confirmation of the diagnosis of PNET, a search for metastases (mainly hepatic), and identification of the main histoprognostic factors. This update focuses on the WHO 2017 histological classification and recent innovations in the preoperative assessment of PNET using conventional and isotopic imaging. The aim is to not only allow the mapping of primary and metastatic lesions but also to predict tumor aggressiveness.

Gastroenteropancreatic neuroendocrine tumours (GEP-NET) - Imaging and staging

Detection of gastroenteropancreatic neuroendocrine tumours (GEP-NETs) and monitoring of treatment response relies mainly on morphological imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). Molecular imaging techniques also in combination with CT (hybrid imaging) greatly benefit patient management, including better localization of occult tumours and better staging. Somatostatin receptor scintigraphy (SRS) and somatostatin receptor (SSTR) positron emission tomography (PET) play a central role in the diagnostic work-up of patients with well-differentiated GEP-NETs. SSTR PET/CT is superior to SRS and should be used whenever available. (18)F-DOPA and (18)F-FDG PET/CT is inferior to SSTR PET/CT at least in patients with well-differentiated GEP-NETs. Both SSTR PET/CT and SRS have limitations, such as relatively low detection rate of benign insulinomas, poorly differentiated GEP-NETs and liver metastases. New innovations such as SSTR PET/MRI, radiolabelled SSTR antagonists and glucagon-like peptide-1 receptor (GLP-1R) agonists might further improve imaging of GEP-NETs.

Insulinoma case series: Experience of a tertiary care center

BACKGROUND

Insulinomas are usually solitary; benign and encapsulated small lesions and majority of them measure <2 cm in diameter. They pose a challenge for pre-operative localization. Definitive treatment is surgical excision of the tumor. Intra-operative ultrasonography (IOUS), transhepatic portal venous sampling (THPVS) and positron emission tomography (PET) scan can be done for tumors not localized by conventional imaging modalities.

MATERIALS AND METHODS

A retrospective study of patients diagnosed with insulinoma during the period 2004-2012 (8 years) was done. Biochemical diagnostic criteria used were plasma concentrations of glucose <55 mg/dl with corresponding insulin level >3.0 μU/ml (18 pmol/L) and C-peptide of >0.6 ng/ml (0.2 nmol/L). The localization of the tumor was done by various modalities namely computed tomography (CT), magnetic resonance imaging (MRI), IOUS, PET and portal venous sampling. The initial localizing technique in most of these patients were CT or MRI imaging, or both and those who were not localized by the above modalities were subjected to PET CT or THPVS or intra-operative ultrasound depending on the initial imaging results and patient's consent. All the modalities were not used in the same patient, but the modalities were decided as per the imaging results, patient's consent and affordability for the procedure.

RESULTS

Ninteen cases of insulinoma aged between 10 and 66 years, with a median age of 47 years were included in the analysis. There were 10 males and nine females. Eighty-three percent of patients presented with pre-prandial hypoglycemia (n = 15). Different modalities were employed for pre-operative localization of these patients out of which 5 (26.31%) cases were localized with CT, 5 (26.31) cases with MRI, 5 (26.31%) with THPVS, 1 (5.26%) case with PET CT, 3 (15.78%) of them could not be localized out of which 2 (10.52%) were localized by IOUS and 1 (5.26%) case the lesion could not be localized. Among 19 cases, 12 underwent surgery out of which one patient underwent distal pancreatectomy as tumor was not localized; eight underwent laparoscopic enucleation; three of them required intra-operative exploration and seven of them were not operated, as they did not give consent for surgery. In all the cases, the size of the insulinoma ranged between 1 and 2 cm.

CONCLUSION

We report our experience with 19 cases of insulinoma and analyze the role of pre- and intra-operative imaging modalities in the surgical management of insulinomas. Most of our cases were symptomatic, and the most common presentation was with pre-prandial hypoglycemia. THPVS, PET scan and intra-operative ultrasound added to diagnostic sensitivity in some cases not localized by CT or MRI.

Pancreatic endocrine tumors

Pancreatic endocrine tumors have been steadily growing in incidence and prevalence during the last two decades, showing an incidence of 4-5/1,000,000 population. They represent a heterogeneous group with very varying tumor biology and prognosis. About half of the patients present clinical symptoms and syndromes related to substances released from the tumors (Zollinger-Ellison syndrome, insulinoma, glucagonoma, etc) and the other half are so-called nonfunctioning tumors mainly presenting with symptoms such as obstruction, jaundice, bleeding, and abdominal mass. Ten percent to 15% of the pancreatic endocrine tumors are part of an inherited syndrome such as multiple endocrine neoplasia type 1 (MEN-1), von Hippel-Lindau (VHL), neurofibromatosis, or tuberousclerosis. The diagnosis is based on histopathology demonstrating neuroendocrine features such as positive staining for chromogranin A and specific hormones such as gastrin, proinsulin, and glucagon. Moreover, the biochemical diagnosis includes measurement of chromogranins A and B or specific hormones such as gastrin, insulin, glucagon, and vasoactive intestinal polypeptide (VIP) in the circulation. In addition to standard localization procedures, radiology (computed tomography [CT] scan, magnetic resonance imaging [MRI], ultrasound [US]), somatostatin receptor scintigraphy, and most recently positron emission tomography with specific isotopes such as (11)C-5 hydroxytryptamin ((11)C-5-HTP), fluorodopa and (68)Ga-1,4,7,10-tetra-azacyclododecane-N,N',N″,N‴-tetra-acetic acid (DOTA)-octreotate are performed. Surgery is still one of the cornerstones in the management of pancreatic endocrine tumors, but curative surgery is rarely obtained in most cases because of metastatic disease. Debulking and other cytoreductive procedures might facilitate systemic treatment. Cytotoxic drugs, biological agents, such as somatostatin analogs, alpha interferons, mammalian target of rapamycin (mTOR) inhibitors and tyrosine kinase inhibitors are routinely used. Tumor-targeted radioactive treatment is available in many centres in Europe and is effective in patients with tumors that express high content of somatostatin receptors type 2 and 5. In the future, treatment will be based on tumor biology and molecular genetics with the aim of so-called personalized medicine.

[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.

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.

Sporadically occurring functional pancreatic endocrine tumors: review of recent literature

PURPOSE OF REVIEW

Pancreatic neuroendocrine tumors are rare neoplasms often associated with a clinical syndrome. Their rarity makes a comprehensive study difficult at any single institution, while their uniqueness makes them desirable for investigation. This review summarizes recent information and advancements concerning pancreatic neuroendocrine tumor diagnosis, imaging characteristics, treatment algorithms, and staging.

RECENT FINDINGS

Insulinomas and gastrinomas comprise the majority of functional pancreatic neuroendocrine tumors. Advances in their identification and diagnostic evaluation, imaging techniques, and treatment algorithms are presented. Furthermore, a new staging classification system has been proposed which may significantly improve the ability to conduct future multi-institutional investigations on pancreatic neuroendocrine tumors.

SUMMARY

Although rare, a thorough understanding of pancreatic neuroendocrine tumors is essential for all physicians due to the wide variety of symptoms with which patients present. Currently, patients are often misdiagnosed for extended periods of time. This review summarizes the recently published literature about diagnosis, imaging, treatment, and staging of pancreatic neuroendocrine tumors.

Fluorine-18-L-dihydroxyphenylalanine (18F-DOPA) positron emission tomography as a tool to localize an insulinoma or beta-cell hyperplasia in adult patients

CONTEXT AND OBJECTIVE

Fluorine-18-L-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET) is a promising method in localizing neuroendocrine tumors. Recently, it has been shown to differentiate focal forms of congenital hyperinsulinism of infancy. The current study was set up to determine the potential of 18F-DOPA PET in identifying the insulin-secreting tumors or beta-cell hyperplasia of the pancreas in adults.

PATIENTS AND METHODS

We prospectively studied 10 patients with confirmed hyperinsulinemic hypoglycemia and presumed insulin-secreting tumor using 18F-DOPA PET. Anatomical imaging was performed with computed tomography (CT) and magnetic resonance imaging (MRI). All patients were operated on, and histological verification was available in each case. Semiquantitative PET findings in the pancreas using standardized uptake values were compared to standardized uptake values of seven consecutive patients with nonpancreatic neuroendocrine tumors.

RESULTS

By visual inspection of 18F-DOPA PET images, it was possible in nine of 10 patients to localize the pancreatic lesion, subsequently confirmed by histological analysis. 18F-DOPA uptake was enhanced in six of seven solid insulinomas and in the malignant insulinoma and its hepatic metastasis. Two patients with beta-cell hyperplasia showed increased focal uptake of 18F-DOPA in the affected areas. As compared to CT or MRI, 18F-DOPA PET was more sensitive in localizing diseased pancreatic tissue.

CONCLUSION

18F-DOPA PET was useful in most patients with insulinoma and negative CT, MRI, and ultrasound results. In agreement with previous findings in infants, preoperative 18F-DOPA imaging seems to be a method of choice for the detection of beta-cell hyperplasia in adults. It should be considered for the detection of insulinoma or beta-cell hyperplasia in patients with confirmed hyperinsulinemic hypoglycemias when other diagnostic work-up is negative.

Surgical treatment of persistent hyperinsulinemic hypoglycemia (PHH) (insulinoma and nesidioblastosis)

BACKGROUND

The persistent hyperinsulinemic hypoglycemia is characterized by clinical symptoms that occur when the blood glucose levels drop below the normal range. Two pathological situations cause this clinical problem: The presence of a tumor of the pancreas secreting excessive amounts of insulin, known as insulinoma, and congenital beta-cell hyperplasia in the pancreas in children and noninsulinoma pancreatogenic hypoglycemia syndrome in adults.

PATIENTS AND METHODS

Clinical characteristic and surgical outcome of a group of 20 patients operated on for this hypoglycemic syndrome; 18 for insulinoma and two for nesidioblastosis in children was studied.

RESULTS

eight of the insulinomas were in the head of the pancreas, two in the body, and the remaining eight in the tail. The surgical technique was enucleation in nine cases, local resection in one case because of suspicious malignancy, and distal pancreatectomy in eight cases. Both children with nesidioblastosis underwent 85% pancreatectomy with splenic preservation. There was no mortality in the study, but three patients developed a low-volume pancreatic fistula after head enucleation.

CONCLUSIONS

Negative results in diagnostic localization together with the small size of the insulinoma represent a poor combination for successful surgery. The intraoperative ultrasonography is the method of choice for the identification of the tumor, as it is able to identify nonpalpable lesions.

[Pancreas. Part II: Tumors]

Adenocarcinoma is the most common malignant pancreatic tumor, affecting the head in 60-70% of cases. By the time of diagnosis, approximately 80% of tumors are unresectable. Helical CT is very effective in detection and staging of adenocarcinoma, with a sensitivity of 76-92% for detection and an accuracy of 80-90% for staging, but it has limitations in the detection of small cancers (< or =2 cm). Multidetector CT (MDCT) has brought substantial improvements with its inherent 3D imaging capability. Mangafodipir-enhanced MRI is a problem-solving tool in the depiction of small cancers following an equivocal CT imaging result. Gadolinium-enhanced 3D gradient-echo MRI is helpful in the assessment of vascular invasion of cancer and in determining the etiology of cystic lesions. Serous cystadenoma is benign, has a lobulated contour and contains innumerable small cysts of 0.1-2 cm in diameter. Mucinous cystic neoplasms are unilocular or multilocular (fewer than six cysts), and the cyst diameter exceeds 2 cm. The presence of solid nodular components should alert the radiologist to suspect cystadenocarcinoma. Neuroendocrine tumors are mostly hypervascular. Diagnosis of insulinoma is a challenge: they are <2 cm in 90% of cases and mostly hypervascular at CT or MRI. A combination of contrast-enhanced MDCT, MRI, endosonography, and/or somatostatin receptor scintigraphy is used to detect these small tumors. This review summarizes the imaging features of the most common pancreatic tumors and discusses the limitations of CT, MRI and endosonography.

Islet Hyperplasia in Adults: Challenge to Preoperatively Diagnose Non-Insulinoma Pancreatogenic Hypoglycemia Syndrome

BACKGROUND

Pancreatic hyperfunctional islet hyperplasia in adults has been more and more frequently described in the literature. Postprandial neuroglycopenia, a negative normal fasting test, negative pancreatic imaging results, and positive intra-arterial calcium stimulation of serum insulin are characteristic. In affected patients the term non-insulinoma pancreatogenic hypoglycemia syndrome (NIPHS) was proposed. MATERIALS AND METHODS/PATIENTS: We also encountered fasting hypoglycemia in such patients and therefore evaluated clinical and biochemical data in patients with NIPHS (n = 11), patients with insulinoma (n = 70), and patients in whom hypoglycemia was ruled out (n = 70).

RESULTS

Patients with NIPHS were younger (median age: 41 years; range: 18-66) and mostly non-obese (median body mass index/BMI: 22.2 kg/m2; range: 19-39) compared with patients with an insulinoma (median age: 50 years; median: BMI 26.1 kg/m2). During an oral glucose tolerance test (OGTT) followed by a standard fasting test, neuroglycopenia was observed postprandially with a mean minimal blood glucose level of 36 +/- 9 mg/dl in 7 out of 11 patients. Spontaneous hypoglycemia during the fast was 38 +/- 5 mg/dl in 8 out of 11 patients. The corresponding insulin levels were 9.2 +/- 9.8 mU/l (OGTT) and 6.8 +/- 5.4 mU/l (fasting), significantly lower than in patients with insulinoma (P < 0.001), but not different from patients without hypoglycemia (P = 0.05). After pancreatic resection 8 patients (73%) were cured with enduring euglycemia. Pathohistological islet abnormalities with hyperplasia, hypertrophy, and microadenomatosis were confirmed in all patients.

CONCLUSION

In patients with postprandial and/or fasting neuroglycopenia NIPHS may be suspected when insulin levels are low but inadequately suppressed and localization studies failed to show a distinct pancreatic tumor.