A review of functional pancreatic neuroendocrine tumors: Exploring the molecular pathogenesis, diagnosis and treatment

Pancreatic neuroendocrine tumors (PanNETs) are a rare subtype of pancreatic cancer and can be divided into functional (30-40%) and nonfunctional subtypes. The different subtypes of functional PanNETs (F-PanNETs) have a variety of classical presentations that raise suspicion for an underlying PanNET. It is estimated that 90% of PanNETs are sporadic, and the PI3K-Akt-mTOR and ATRX/DAXX signaling pathways have been recognized as key genetic pathways implicated in the pathogenesis. The other 10% of PanNETs may occur in the context of familial cancer syndromes such as MEN1. Chromogranin A is the most useful biomarker currently; however, several studies have shown limitations with its use, especially its prognostic value. Synaptophysin is a novel biomarker which has shown promising preliminary results however its use clinically has yet to be established. Blood tests assessing hormone levels, cross-sectional imaging, and endoscopic ultrasound remain at the core of establishing a diagnosis of F-PanNET. The treatment options for F-PanNETs include surgical methods such as enucleation, systemic therapies like chemotherapy and novel targeted therapies such as everolimus. The prognosis for F-PanNETs is more favorable than for nonfunctional PanNETs, however metastatic disease is associated with poor survival outcomes. Researchers should also focus their efforts on identifying novel pathways implicated in the pathogenesis of F-PanNETs in order to develop new targeted therapies that may reduce the need for surgical intervention and on the establishment of novel biomarkers that may reduce the need for invasive testing and allow for earlier detection of F-PanNETs.

Pathological features in non-neoplastic congenital and adult hyperinsulinism: from nesidioblastosis to current terminology and understanding

Nesidioblastoma and nesidioblastosis were terms given to neoplastic and non-neoplastic lesions of the pancreas associated with pancreatogenous hyperinsulinaemic hypoglycaemia. While nesidioblastoma was rapidly replaced by islet cell tumour, nesidioblastosis, defined as the proliferation of islet cells budding off from pancreatic ducts, was the diagnostic term associated with congenital hyperinsulinism of infancy (CHI) and adult non-neoplastic hyperinsulinaemic hypoglycaemia (ANHH). When it was shown that nesidioblastosis was not specific for CHI or ANHH, it was no longer applied to CHI but kept for the morphological diagnosis of ANHH. In severe CHI cases, a diffuse form with hypertrophic ß-cells in all islets can be distinguished from a focal form with hyperactive ß-cells changes in a limited adenomatoid hyperplastic area. Genetically, mutations were identified in several ß-cell genes involved in insulin secretion. Most common are mutations in the ABCC8 or KCNJ11 genes, solely affected in the diffuse form and associated with a focal maternal allelic loss on 11p15.5 in the focal form. Focal CHI can be localized by 18F-DOPA-PET and is thus curable by targeted resection. Diffuse CHI that fails medical treatment requires subtotal pancreatectomy. In ANHH, an idiopathic form can be distinguished from a form associated with gastric bypass, in whom GLP1-induced stimulation of the ß-cells is discussed. While the ß-cells in idiopathic ANHH are diffusely affected and are either hypertrophic or show only little changes, it is controversial whether there is a ß-cell increase or ß-cell hyperactivity in patients with gastric bypass. Recognizing morphological signs of ß-cell hyperactivity needs a good knowledge of the non-neoplastic endocrine pancreas across all ages.

Big insulin-like growth factor 2-producing multiple solitary fibrous tumors treated with debulking surgery: A case report

BACKGROUND

Non-islet cell tumor hypoglycemia (NICTH) is a rare paraneoplastic syndrome caused by a tumor-producing high molecular weight form of insulin-like growth factor 2 (IGF2) known as big IGF2. The only curative treatment for this condition is surgical resection of the responsible tumors. However, this may not be feasible in cases with multiple metastases at diagnosis of NICTH, and no standard treatment strategy for multiple tumors has been established. The effects of pharmacological therapies including somatostatin analogs are often inefficient and remain difficult to predict.

CASE DESCRIPTION

A 68-year-old man was admitted to our hospital due to impaired consciousness and severe hypoglycemia. His medical history included diagnosis of a left temporal solitary fibrous tumor (SFT) at the age of 48 years, after which local recurrent and metastatic tumors were repeatedly resected. Four years before admission, multiple intraabdominal and subcutaneous tumors were detected and, being asymptomatic, were managed conservatively. Laboratory exam on admission demonstrated hypoglycemia accompanied with low serum insulin and IGF1 levels. Computed tomography (CT) scan revealed multiple intraabdominal and subcutaneous tumors increasing in size. Serum big IGF2 was detected on immunoblot analysis, and he was diagnosed as NICTH. In addition, tumor uptake was observed on ⁶⁸Ga-labelled 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid-d-Phe¹-Tyr³-octreotide positron emission tomography/CT (DOTATOC-PET/CT). Since larger tumor is more suspicious about responsible producibility of big IGF2, we planned to resect large ones preferentially and reduce the amounts of residual tumors. Debulking surgery was performed by removing eleven intraabdominal tumors; the hypoglycemia was then completely corrected. Histological analyses revealed the resected tumors to be metastases of SFT having somatostatin receptor 2 expression. In immunoblot analysis, the resected tumors were found to be positive for big IGF2; serum big IGF2 was undetectable after surgery.

CONCLUSION

We present a case of NICTH with multiple metastatic SFTs. We strategically performed debulking surgery, which led to remission of hypoglycemia. This result demonstrates a pioneering practical solution for NICTH cases with multiple tumors. In addition, in cases of SFTs presenting with NICTH, positivity of DOTATOC-PET/CT as well as single-dose administration of octreotide may be predictive of the efficacy of somatostatin-based therapy.

Case report: Metastatic pancreatic neuroendocrine tumour associated with portal vein thrombosis; successful management with subsequent pregnancies

BACKGROUND

Splanchnic vein thrombosis due to co-existing metastatic pancreatic neuroendocrine tumour (pNET) and JAK2V617F mutation is a rare condition.

CASE REPORT

Here we present a case of a young woman with complete remission of a non-functioning grade 2 pNET with unresectable liver metastases, coexisting with JAK2V617F mutation. Splenectomy and distal pancreatectomy were performed. Neither surgical removal, nor radiofrequency ablation of the liver metastases was possible. Therefore, somatostatin analogue (SSA) and enoxaparine were started. Peptide receptor radionuclide therapy (PRRT) was given in 3 cycles 6-8 weeks apart. Genetic testing revealed no multiple endocrine neoplasia type 1 (MEN-1) gene mutations. After shared decision making with the patient, she gave birth to two healthy children, currently 2 and 4 years old. On pregnancy confirmation, SSA treatment was interrupted and resumed after each delivery. Ten years after the diagnosis of pNET, no tumour is detectable by MRI or somatostatin receptor scintigraphy. PRRT followed by continuous SSA therapy, interrupted only during pregnancies, resulted in complete remission and enabled the patient to complete two successful pregnancies.

Surgical treatment of pancreatic islet cell tumor: report of 44 cases

BACKGROUND/AIMS

Open approach was the conventional ways for surgical treatment of pancreatic islet cell tumor. The study was to report the outcome of open approach with pancreatic islet cell tumor in a single institution in China.

METHODOLOGY

Forty-four consecutive pancreatic islet cell tumor patients who underwent surgical treatment were retrospectively analyzed.

RESULTS

There were 16 pancreatic nonfunctioning islet cell tumor (PNIT) patients and 28 functioning islet cell tumor patients which were insulinoma. Seventeen PNIT were found and larger than media size of thirty-nine insulinoma (4.53 +/- 2.67 vs. 1.87 +/- 0.86, p < 0.05) in diameter. The size of malignant and benign PNIT has a significant difference (6.33 +/- 2.06 vs. 3.45 +/- 2.51, p < 0.05 ), but not in insulinoma. Among PNIT, distal pancreatectomy plus splenectomy were required in 8 patients, while segmental pancreatectomy was performed in 3 cases. In addition, 1 and 4 patients received pancreatoduodenectomy and tumor enucleation respectively. Seventeen insulinomas patients (60.7%) underwent enucleation, and 2 patients (7.1%) underwent distal pancreatectomy with splenectomy. Segmental pancreatectomy, pancreatoduodenectomy and distal pancreatectomy preserving spleen was performed in 2, 4 and 3 cases respectively. The percentage was zero in-hospital death. The morbidity was 6.2% (1/16) for PNIT and 28.6% (8/28) for insulinomas.

CONCLUSIONS

Open surgery remains a nice way in the management of pancreatic islet cell tumor at least in our institution.

Gastric neuroendocrine carcinoma with non-islet cell tumor hypoglycemia associated with enhanced production of insulin-like growth factor II

A 75-year-old man was admitted to the hospital with a loss of consciousness. His blood glucose level was 24 mg/dL. Abdominal computed tomography revealed multiple metastatic lesions in the liver, while upper endoscopy disclosed advanced gastric cancer. The hypoglycemia was refractory despite the administration of glucose and steroid therapy. The patient died within one month of admission. An autopsy revealed neuroendocrine-type gastric cancer, which, on examination with immunohistochemistry, was found to be negative for insulin and insulin-like growth factor I and positive for insulin-like growth factor II (IGF-II). The patient was diagnosed as having gastric cancer with non-islet cell tumor hypoglycemia (NICTH) caused by IGF-II.

Pancreatic and peri-pancreatic lesions mimic pancreatic islet cell tumor in multidetector computed tomography

OBJECTIVE

This pictorial review aimed to summarize the most possible differential diagnosis of pancreatic islet cell tumor (PICT).

DATA SOURCES

Data used in this review were mainly from Medline and Pubmed in English. And all clinical images in this review were from Department of Radiology, Peking Union Medical College Hospital, Beijing, China.

STUDY SELECTION

Cases of pancreatic cystadenoma, solid pseudo-papillary tumor of the pancreas, pancreatic metastasis, pancreatic adenocarcinoma, para-pancreatic neuroendocrine tumors, Castleman disease, gastrointestinal stromal tumor, splenic artery aneurysm and accessory spleen were selected in this pictorial review for differential diagnosis of PICT.

RESULTS

Careful analysis of imaging features and correlation with the clinical manifestations may allow a more specific diagnosis. It is also important that the radiologist is familiar with the anatomic variants and disease entities which mimic pancreatic islet cell tumor in order to avoid an improper treatment protocol.

CONCLUSIONS

Many congenital anatomic variants or other pancreatic and peri-pancreatic diseases may mimic MDCT appearance of pancreatic islet cell tumor. Radiological, clinical and pathological characteristics should be considered for the final diagnosis.

Targeting the ANG2/TIE2 axis inhibits tumor growth and metastasis by impairing angiogenesis and disabling rebounds of proangiogenic myeloid cells

Tumor-infiltrating myeloid cells convey proangiogenic programs that counteract the efficacy of antiangiogenic therapy. Here, we show that blocking angiopoietin-2 (ANG2), a TIE2 ligand and angiogenic factor expressed by activated endothelial cells (ECs), regresses the tumor vasculature and inhibits progression of late-stage, metastatic MMTV-PyMT mammary carcinomas and RIP1-Tag2 pancreatic insulinomas. ANG2 blockade did not inhibit recruitment of MRC1(+) TIE2-expressing macrophages (TEMs) but impeded their upregulation of Tie2, association with blood vessels, and ability to restore angiogenesis in tumors. Conditional Tie2 gene knockdown in TEMs was sufficient to decrease tumor angiogenesis. Our findings support a model wherein the ANG2-TIE2 axis mediates cell-to-cell interactions between TEMs and ECs that are important for tumor angiogenesis and can be targeted to induce effective antitumor responses.

Systematic comparison of sporadic and syndromic pancreatic islet cell tumors

Pancreatic islet cell tumors (ICTs) occur as sporadic neoplasias or as a manifestation of multiple endocrine neoplasia type 1 (MEN1) and von Hippel-Lindau disease (VHL). Molecular classification of ICTs is mandatory for timely diagnosis and surveillance. Systematic comparison of VHL-ICTs and sporadic ICTs has been lacking. Our registry-based approaches used the German NET-Registry with 259 patients with neuroendocrine tumors (NETs), who were primarily diagnosed with NETs, and the German VHL-Registry with 485 molecular genetically confirmed patients who had undergone magnetic resonance imaging or computed tomography of the abdomen. All patients provided blood DNA for testing of the MEN1 and VHL genes for intragenic mutations and large deletions. In the NET-Registry, 9/101 patients (8.9%) with ICTs had germline mutations, 8 in MEN1 and 1 in VHL. In the VHL-Registry, prevalence of NETs was 52/487 (10.6%), and all were ICTs. Interestingly, of those with VHL p.R167W, 47% developed ICTs, compared to 2% of those with p.Y98H. In total, there were 92 truly sporadic, i.e. mutation-negative ICT patients. Comparing these with the 53 VHL-ICT patients, the statistically significant differences were predominance of female gender (P=0.01), multifocal ICTs (P=0.0029), and lower malignancy rate (P<0.001) in VHL-ICTs compared to sporadic cases. VHL was prevalent in <0.5% of NETs, while NETs occur in ∼10% of VHL, virtually exclusively as ICTs, which are rarely the first presentation. Patients with NETs should not be subjected to genetic testing of the VHL gene, unless they have multifocal ICTs, other VHL-associated tumors, and/or a family history for VHL.

Multiple endocrine neoplasia type 1 (MEN1)

Multiple Endocrine Neoplasia type 1 (MEN1) is an autosomal-dominant disorder characterised by the occurrence of tumours of the parathyroids, pancreas and anterior pituitary. The MEN1 gene, consists of 10 exons that encode a 610-amino acid protein referred to as Menin. Menin is predominantly a nuclear protein that has roles in transcriptional regulation, genome stability, cell division and proliferation. Germ-line mutations usually result in MEN1 or occasionally in an allelic variant referred to as Familial Isolated Hyperparathyroidism (FIHP). MEN1 tumours frequently have loss of heterozygosity (LOH) of the MEN1 locus, which is consistent with a tumour suppressor role of MEN1. Furthermore, somatic abnormalities of MEN1 have been reported in MEN1 and non-MEN1 endocrine tumours. To date, over 1300 mutations have been reported, and the majority (>70%) of these are predicted to lead to truncated forms of Menin. The mutations are scattered throughout the >9 kb genomic sequence of the MEN1 gene. Four, which consist of c.249_252delGTCT (deletion at codons 83-84), c.1546_1547insC (insertion at codon 516), c.1378C>T (Arg460Ter) and c.628_631delACAG (deletion at codons 210-211) have been reported to occur frequently in 4.5%, 2.7%, 2.6% and 2.5% of families, respectively. However, a comparison of the clinical features in patients and their families with the same mutations reveals an absence of phenotype-genotype correlations. The majority of MEN1 mutations are likely to disrupt the interactions of Menin with other proteins and thereby alter critical events in cell cycle regulation and proliferation.

Cleaved caspase-3 immunocytochemical staining for pancreatic islets and pancreatic endocrine tumors: A potential marker for biological malignancy

AIMS

Involvement of caspase (C)-3 has been implicated in β-cells from diabetic subjects. This study is aimed to immunocytochemically identify cleaved caspase-3 (CC-3) positive cells in pancreatic endocrine tumors (PETs) compared with control islets.

RESULTS

Control islets revealed some CC-3 positive cells, ranging from 3.6 to 7.3% of total islet cells. Small islets in the pseudocapsule of PETs showed higher immunopositive cells at about 9% for CC -3, suggesting an accelerated apoptosis in these compressed, elongated islets before proceeding to imminent cell death. Majority of primary PETs except 9 cases were negative for CC -3 immunostaining: five insulinomas, one somatostatinoma, one gastrinoma and one pancreatic peptidoma (PPoma) were positive for CC -3.

METHODS

Using commercially available rabbit anti-CC-3, immunocytochemical staining was performed in 42 cases of PETs compared with control islets.

CONCLUSIONS/INTERPRETATION

Majority of primary PETs (28/37, 76%) were negative for CC-3, suggesting that majority of PETs are not on apoptotic program of the normal islets. Since 21 of 24 (88%) of potentially malignant primary non-β-cell PETs were negative, whereas 5 of 12 (42%) benign insulinomas were positive for CC-3 immunostaining, CC-3 negative immunostaining may serve as a possible malignant marker for all PETs.

Somatostatin receptor subtype 5 (SSTR5) mRNA expression is related to histopathological features of cell proliferation in insulinomas

Insulinomas are rare endocrine neoplasias that constitute the most frequent islet cell tumours. Somatostatin (SST) analogs are tentatively used to inhibit insulin secretion and control tumour growth in patients with local invasion or inoperative metastasis, but variable responses have been reported. Data regarding somatostatin receptor (SSTR) subtypes expression in insulinomas are conflicting. In this study, we evaluated 16 cases of primary insulinomas (including four primary plurihormonal tumours) and two hepatic metastases. Histopathological and immunohistochemical analysis for some features associated with tumour aggressiveness and semi-quantitative RT-PCR for SSTR1-5 and real-time qPCR for SSTR5 were performed. SSTR subtypes 1, 3, and 5 were expressed in 100%, SSTR2 in 89%, and SSTR4 only in 22% of the insulinomas. SSTR5 mRNA was positively correlated with histopathological features related to tumour aggressiveness (large tumour diameter, well-differentiated endocrine tumour with uncertain behaviour and higher number of cells with nuclear atypia). SSTR5 mRNA expression in primary insulinomas was lower than in primary plurihormonal tumours (P < 0.05). The observed positive correlation between SSTR5 expression and tumour size suggests that the use of SST analogues more specific to SSTR5 in the treatment of insulinomas deserves attention.

Zollinger-Ellison phenotype in the absence of hypergastrinemia and islet-cell tumor

Patients with the Zollinger-Ellison syndrome are characterized by islet-cell tumors, striking gastric acid hypersecretion, and peptic ulcer disease. They often experience severe abdominal pain, diarrhea, and gastrointestinal bleeding with potentially life-threatening consequences. It is a rare syndrome caused by non-beta cell islet-cell tumors (gastrinomas) located in or in proximity to the pancreas. These tumors freely secrete gastrin, a peptide hormone that serves as a powerful stimulant of gastric acid secretion. Exuberant secretion of gastrin from the gastrinomas produces severe gastric acid hypersecretion that often leads to impressive peptic ulcer disease and the constellation of symptoms listed above. We describe a patient presenting with clinical manifestations characteristic of the ZES with strikingly elevated gastric acid secretion,multiple ulcers in the first and second portions of the duodenum and diarrhea, but in absence of islet-cell tumor and/or hypergastrinemia.

Serpins inhibit the toxicity of amyloid peptides

The amyloid plaque in Alzheimer's disease (AD) contains numerous proteins, some of which may be relevant to the pathogenesis of the disease. The serine protease inhibitor alpha1-antichymotrypsin is specifically localized in AD plaques. It is shown here that alpha1-antichymotrypsin and several other serine protease inhibitors (serpins) inhibit the toxicity of amyloid peptides on primary cortical nerve cell cultures as well as a clonal cell line. This inhibition of toxicity is not mediated via the serpin enzyme complex receptor, the transferrin receptor, or by interference with the polymerization of amyloid fibrils. Since a variety of synthetic serine protease inhibitors mimic the effects of serpins on amyloid toxicity, it is likely that the antiprotease activities of serpins are responsible for their biological effects.