What Is New in the 2017 World Health Organization Classification and 8th American Joint Committee on Cancer Staging System for Pancreatic Neuroendocrine Neoplasms?

Adrenocorticotropic Hormone-Producing Pancreatic Neuroendocrine Neoplasms: A Systematic Review

OBJECTIVE

Adrenocorticotropic hormone-producing pancreatic neuroendocrine neoplasm (ACTHoma) is an exceedingly rare type of pancreatic neuroendocrine neoplasm (pNEN) that often causes ectopic adrenocorticotropic hormone syndrome. These neoplasms have been found to be very aggressive and challenging to treat. The current systematic review aimed to analyze the clinical features, immunohistochemical characteristics, diagnosis, therapy, and prognosis of ACTHoma.

METHODS

A systematic review of the English- and Chinese-language literature was performed. PubMed, EMBASE, and Wanfang databases were searched to identify articles about ACTHoma in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines.

RESULTS

A total of 210 studies encompassing 336 patients diagnosed with ACTHoma were selected for the systematic review, including 16 Chinese patients.

CONCLUSION

ACTHoma was more common in women (66.4%), and the mean age was 44.7 years. Tumors were generally large, and the mean tumor size was 4.43 cm. The incidence of clinical manifestations was: hypokalemia, 69.3%; diabetes, 63.2%; weakness, 60.1%, hypertension, 56.4%; moon face 41.1%; and edema, 37.4%. These tumors are more commonly found in the tail of pancreas, and the most frequent site of metastasis was the liver. The pNENs or other functioning pNENs could evolve into ACTHoma. ACTHoma is a very rare disease, and the mean follow-up time was 28.3 months.

Pancreatic Neuroendocrine Tumor presenting as a diffuse pancreatic enlargement, case report and review of literature

Pancreatic neuroendocrine tumors are rare neoplasms that comprise 1-2% of all pancreatic tumors. However, they are the second most common solid pancreatic neoplasms. They have a wide range of imaging appearances and they can show common to very rare imaging presentations. Most of the time they are solitary well-marginated enhancing solid mass arising in a certain aspect of the pancreas. We present a case report of a 41-year-old female who underwent clinical work-up for abdominal pain, loss of appetite and weight loss for the past year. Ultrasound, computed tomography, and magnetic resonance imaging show diffuse homogenous pancreatic enlargement without contour deformity or a focal mass. Lymphoma and autoimmune pancreatitis were suggested based on imaging findings but IGg4 level and other lab data were normal. Endoscopic ultrasonography confirmed the diffuse enlargement of the pancreas without peripheral structures involvement. The pathological results of multiple fine-needle aspiration biopsy from all parts of the enlarged pancreas revealed a low-grade neuroendocrine tumor.

Malignant potential of small pancreatic neuroendocrine neoplasm and its risk factors: A multicenter nationwide study

BACKGROUND

Pancreatic neuroendocrine neoplasms (PNENs) show heterogeneous biological behavior, and most small PNENs show indolent features. Consequently, selected cases can be considered for observation only, according to the National Comprehensive Cancer Network guideline, however, supporting clinical evidence is lacking. We investigated the clinical course of small PNENs and their risk factors for malignant potential.

METHODS

A total of 158 patients with small pathologically confirmed PNENs ≤2 cm in initial imaging were retrospectively enrolled from 14 institutions. The primary outcome was any metastasis or recurrence event during follow-up.

RESULTS

The median age was 57 years (range, 22-82 years), and 86 patients (54%) were female. The median tumor size at initial diagnosis was 13 mm (range, 7-20 mm). PNENs were pathologically confirmed by surgery in 137 patients and by EUS-guided fine needle aspiration biopsy (EUS-FNAB) in 21 patients. Eight patients underwent EUS-FNAB followed by surgical resection. The results of WHO grade were available in 150 patients, and revealed 123 grade 1, 25 grade 2, and 2 neuroendocrine carcinomas. A total of 145 patients (92%) underwent surgical resection, and three patients had regional lymph node metastasis. During the entire follow-up of median 45.6 months, 11 metastases or recurrences (7%) occurred. WHO grade 2 (HR 13.97, 95% CI 2.60-75.03, p = 0.002) was the only predictive factor for malignant potential in multivariable analysis.

CONCLUSIONS

WHO grade is responsible for the malignant potential of small PNENs ≤2 cm. Thus, EUS-FNAB could be recommended in order to provide early treatment strategies of small PNENs.

Role of Somatostatin Receptor in Pancreatic Neuroendocrine Tumor Development, Diagnosis, and Therapy

Pancreatic neuroendocrine tumors (pNETs) are rare and part of the diverse family of neuroendocrine neoplasms (NENs). Somatostatin receptors (SSTRs), which are widely expressed in NENs, are G-protein coupled receptors that can be activated by somatostatins or its synthetic analogs. Therefore, SSTRs have been widely researched as a diagnostic marker and therapeutic target in pNETs. A large number of studies have demonstrated the clinical significance of SSTRs in pNETs. In this review, relevant literature has been appraised to summarize the most recent empirical evidence addressing the clinical significance of SSTRs in pNETs. Overall, these studies have shown that SSTRs have great value in the diagnosis, treatment, and prognostic prediction of pNETs; however, further research is still necessary.

Efficacy of 177Lu-Dotatate Induction and Maintenance Therapy of Various Types of Neuroendocrine Tumors: A Phase II Registry Study

Peptide receptor radionuclide therapy (PRRT) has been recently established as a treatment option for progressive gastro-entero-pancreatic neuroendocrine tumors (NETs) including four 200 mCi induction cycles. The purpose of this phase 2 trial is to expand use of PRRT to different types of NETs with the application of dose adjustment and evaluate value of maintenance therapy in patients who had disease control on induction therapy. Forty-seven PRRT naïve NET patients with different primary origin received ¹⁷⁷Lu-DOTATATE induction therapy, ranging from 75 to 150 mCi per cycle, based on patients’ clinical status such as liver and renal function, extent of metastases, and previous therapies. Thirty-four patients underwent additional maintenance therapy (50–100 mCi per cycle) following induction course until they developed disease progression. The estimated median progression-free survival (PFS) was 36.1 months. The median PFS in our MNET subgroup was 47.7 months, which is markedly longer than NETTER-1 trial with median PFS of 28.4 months. The median PFS was significantly longer in patients who received PRRT as first-line treatment after disease progression on somatostatin analogs compared to patients who received other therapies first (p-value = 0.04). The total disease response rate (DRR) and disease control rate (DCR) was 32% and 85% based on RECIST 1.1 and 45% and 83% based on Choi criteria. This trial demonstrates longer PFS with the addition of low dose maintenance therapy to induction therapy compared to NETTER-1 trial that only included induction therapy. Also, we observed considerable efficacy of PRRT in various types of advanced NETs.

Role of PET/CT and Therapy Management of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine neoplasms (panNENs) are heterogeneous neoplasms with neuroendocrine differentiation that show peculiar clinical and histomorphological features, with variable prognosis. In recent years, advances in knowledge regarding the pathophysiology and heterogeneous clinical presentation, as well as the availability of different diagnostic procedures for panNEN diagnosis and novel therapeutic options for patient clinical management, has led to the recognition of the need for an active multidisciplinary discussion for optimal patient care. Molecular imaging with positron emission tomography/computed tomography (PET/CT) has become indispensable for the management of panNENs. Several PET radiopharmaceuticals can be used to characterize either panNEN receptor expression or metabolism. The aim of this review is to offer an overview of all the currently used radiopharmaceuticals and of the new upcoming tracers for pancreatic neuroendocrine tumors (panNETs), and their clinical impact on therapy management. [68Ga]Ga-DOTA-peptide PET/CT (SSA-PET/CT) has high sensitivity, specificity, and accuracy and is recommended for the staging and restaging of any non-insulinoma well-differentiated panNEN cases to carry out detection of unknown primary tumor sites or early relapse and for evaluation of in vivo somatostatin receptors expression (SRE) to select patient candidates for peptide receptor radiometabolic treatment (PRRT) with 90Y or 177Lu and/or cold analogs. SSA-PET/CT also has a strong impact on clinical management, leading to a change in treatment in approximately a third of the cases. Its role for treatment response assessment is still under debate due to the lack of standardized criteria, even though some semiquantitative parameters seem to be able to predict response. [18F]FDG PET/CT generally shows low sensitivity in small growing and well-differentiated neuroendocrine tumors (NET; G1 and G2), while it is of utmost importance in the evaluation and management of high-grade NENs and also provides important prognostic information. When positive, [18F]FDG PET/CT impacts therapeutical management, indicating the need for a more aggressive treatment regime. Although FDG positivity does not exclude the patient from PRRT, several studies have demonstrated that it is certainly useful to predict response, even in this setting. The role of [18F]FDOPA for the study of panNET is limited by physiological uptake in the pancreas and is therefore not recommended. Moreover, it provides no information on SRE that has crucial clinical management relevance. Early acquisition of the abdomen and premedication with carbidopa may be useful to increase the accuracy, but further studies are needed to clarify its utility. GLP-1R agonists, such as exendin-4, are particularly useful for benign insulinoma detection, but their accuracy decreases in the case of malignant insulinomas. Being a whole-body imaging technique, exendin-PET/CT gives important preoperative information on tumor size and localization, which is fundamental for surgical planning as resection (enucleation of the lesion or partial pancreatic resection) is the only curative treatment. New upcoming tracers are under study, such as promising SSTR antagonists, which show a favorable biodistribution and higher tumor-to-background ratio that increases tumor detection, especially in the liver. [68Ga]pentixafor, an in vivo marker of CXCR4 expression associated with the behavior of more aggressive tumors, seems to only play a limited role in detecting well-differentiated NET since there is an inverse expression of SSTR2 and CXCR4 in G1 to G3 NETs with an elevation in CXCR4 and a decrease in SSTR2 expression with increasing grade. Other tracers, such as [68Ga]Ga-PSMA, [68Ga]Ga-DATA-TOC, [18F]SiTATE, and [18F]AlF-OC, are also under investigation.

Clinical Features and Long-Term Survival of Metastatic Hepatic Neuroendocrine Neoplasms Secondary to Gastroenteropancreatic Site: An Analysis by Applying the Grading Classification

Method

Data of patients who were surgically treated and clinicopathologically diagnosed as (MH)-NENs secondary to (GEP)-NENs at West China Hospital of Sichuan University from January 2006 to December 2018 were retrospectively collected and analyzed by the grading classification for (GEP)-NENs.

Results

We identified 150 patients with (MH)-NENs secondary to (GEP)-NENs, including 10 patients with G1 NETs, 26 with G2 NETs, 33 with G3 NETs, and 81 with G3 NECs. There were significant differences between patients with G1/G2/G3 NETs and those with G3 NECs, such as age at diagnosis (P=0.041), synchronous liver lesion (P=0.032), incidental diagnosis (P=0.014), tumor largest diameter (P=0.047), vascular invasion (P=0.017), and extrahepatic metastatic disease (P=0.029). The estimated 3-year overall survival for patients with G1 NETs, G2 NETs, G3 NETs, and G3 NECs was 100%, 79.4%, 49.5%, and 20.7%, respectively (P < 0.001). The survival of G1 NETs or G2 NETs was significantly better than that of G3 NETs (P=0.013, P=0.037, respectively) and G3 NECs (P=0.001, P < 0.001; respectively). Patients with G3 NECs present notably worse survival than those with G3 NETs (P=0.012), while survival comparison between G1 NETs and G2 NETs was not statistically different (P=0.131). The grading classification for (GEP)-NENs was an effective independent predictor of survival for (MH)-NENs secondary to (GEP)-NENs (hazard ratio: 4.234; 95% confidence intervals: 1.984–6.763; P=0.003).

Conclusion

Our demonstration revealed that the grading classification for (GEP)-NENs could well stratify (MH)-NENs secondary to (GEP)-NENs into prognostic groups and supported its wide use in clinical practice.

Pancreatic neuroendocrine tumors (pNETs): the predictive value of MDCT characteristics in the differentiation of histopathological grades

PURPOSE

To investigate the correlation between multiple detector computed tomography (MDCT) features of pancreatic neuroendocrine tumors (pNETs) and histopathologic grade and find valuable imaging criteria for grade prediction.

MATERIAL AND METHODS

MDCT of 61 patients with 65 masses, which pNETs were approved histopathologically, underwent revision retrospectively. Each MDCT was evaluated for various radiologic characteristics. Absolute and relative (R: tumor/pancreas, D: tumor-pancreas) tumor enhancements were calculated in multiple post contrast phases.

RESULTS

61 patients [mean age = 50.70 ± 14.28 y/o and 30(49.2%) were male] were evaluated and classified into 2 groups histopathologically: G₁: 32 (49.2%) and G_2,3: 33 (50.8%). Significant relationships were observed between histopathologic tumor grade regarding age (p = 0.006), the longest tumor size (p = 0.006), presence of heterogeneity (p < 0.0001), hypodense foci in delayed phase (p = 0.004), lobulation (p = 0.002), vascular encasement (p < 0.0001), adjacent organ invasion (p = 0.01), presence (p < 0.0001) and number (0.02) of liver metastases, presence of lymphadenopathy with short axis of more than 10 mm (LAP) (p = 0.008), pathologic lymph node size (p = 0.004), relative (R and D) (p = 0.05 and 0.02, respectively), and percentage of arterial hyper-enhancing area (p = <0.0001). Tumor grades, however, had no significant relationship with gender, tumor location, tumor outline, calcification, cystic change, or pancreatic (PD) or biliary duct (BD) dilation (p = 0.21, 0.60, 0.05, 0.05 1, 0.10, and 0.51, respectively). Then, we suggested a novel imaging criteria consisting of six parameters (tumor size > 33 mm, relative (R) tumor enhancement in arterial phase ≤ 1.33, relative (D) tumor enhancement in arterial phase ≤ 16.5, percentage of arterial hyper-enhancing area ≤ 75%, vascular encasement, and lobulation), which specificity and accuracy of combination of all findings (6/6) for predicting G_2,3 were 100% and 70.1%, respectively. The highest accuracy (84.21%) was seen in combinations of at least 4 of 6 findings, with 80.00% sensitivity, 87.5% specificity, 83.33% PPV, and 84.85% NPV.

CONCLUSION

We suggested reliable imaging criteria with high specificity and accuracy for predicting the histopathologic grade of pNETs.

Gastrointestinal neuroendocrine tumors in 2020

Gastrointestinal neuroendocrine tumors are rare slow-growing tumors with distinct histological, biological, and clinical characteristics that have increased in incidence and prevalence within the last few decades. They contain chromogranin A, synaptophysin and neuron-specific enolase which are necessary for making a diagnosis of neuroendocrine tumor. Ki-67 index and mitotic index correlate with cellular proliferation. Serum chromogranin A is the most commonly used biomarker to assess the bulk of disease and monitor treatment and is raised in both functioning and non-functioning neuroendocrine tumors. Most of the gastrointestinal neuroendocrine tumors are non-functional. World Health Organization updated the classification of neuroendocrine tumors in 2017 and renamed mixed adenoneuroendocrine carcinoma into mixed neuroendocrine neoplasm. Gastric neuroendocrine tumors arise from enterochromaffin like cells. They are classified into 4 types. Only type I and type II are gastrin dependent. Small intestinal neuroendocrine tumor is the most common small bowel malignancy. More than two-third of them occur in the terminal ileum within 60 cm of ileocecal valve. Patients with small intestinal neuroendrocrine tumors frequently show clinical symptoms and develop distant metastases more often than those with neuroendocrine tumors of other organs. Duodenal and jejuno-ileal neuroendocrine tumors are distinct biologically and clinically. Carcinoid syndrome generally occurs when jejuno-ileal neuroendocrine tumors metastasize to the liver. Appendiceal neuroendocrine tumors are generally detected after appendectomy. Colonic neuroendocrine tumors generally present as a large tumor with local or distant metastasis at the time of diagnosis. Rectal neuroendocrine tumors are increasingly being diagnosed since the implementation of screening colonoscopy in 2000. Gastrointestinal neuroendocrine tumors are diagnosed and staged by endoscopy with biopsy, endoscopic ultrasound, serology of biomarkers, imaging studies and functional somatostatin scans. Various treatment options are available for curative and palliative treatment of gastrointestinal neuroendocrine tumors.

Pancreatic Neuroendocrine Neoplasms: 2020 Update on Pathologic and Imaging Findings and Classification

Pancreatic neuroendocrine neoplasms (panNENs) are heterogeneous neoplasms with neuroendocrine differentiation that show characteristic clinical, histomorphologic, and prognostic features; genetic alterations; and biologic behavior. Up to 10% of panNENs develop in patients with syndromes that predispose them to cancer, such as multiple endocrine neoplasia type 1, von Hippel-Lindau disease, tuberous sclerosis complex, neurofibromatosis type 1, and glucagon cell adenomatosis. PanNENs are classified as either functioning tumors, which manifest early because of clinical symptoms related to increased hormone production, or nonfunctioning tumors, which often manifest late because of mass effect. PanNENs are histopathologically classified as well-differentiated pancreatic neuroendocrine tumors (panNETs) or poorly differentiated pancreatic neuroendocrine carcinomas (panNECs) according to the 2010 World Health Organization (WHO) classification system. Recent advances in cytogenetics and molecular biology have shown substantial heterogeneity in panNECs, and a new tumor subtype, well-differentiated, high-grade panNET, has been introduced. High-grade panNETs and panNECs are two distinct entities with different pathogenesis, clinical features, imaging findings, treatment options, and prognoses. The 2017 WHO classification system and the eighth edition of the American Joint Committee on Cancer staging system include substantial changes. Multidetector CT, MRI, and endoscopic US help in anatomic localization of the primary tumor, local-regional spread, and metastases. Somatostatin receptor scintigraphy and fluorine 18-fluorodeoxyglucose PET/CT are helpful for functional and metabolic assessment. Knowledge of recent updates in the pathogenesis, classification, and staging of panNENs and familiarity with their imaging findings allow optimal patient treatment. ^©RSNA, 2020.

Systemic Treatment Selection for Patients with Advanced Pancreatic Neuroendocrine Tumours (PanNETs)

Pancreatic neuroendocrine tumours (PanNETs) are rare diseases and a good example of how research is not only feasible, but also of crucial importance in the scenario of rare tumours. Many clinical trials have been performed over the past two decades expanding therapeutic options for patients with advanced PanNETs. Adequate management relies on optimal selection of treatment, which may be challenging for clinicians due to the fact that multiple options of therapy are currently available. A number of therapies already exist, which are supported by data from phase III studies, including somatostatin analogues and targeted therapies (sunitinib and everolimus). In addition, chemotherapy remains an option, with temozolomide and capecitabine being one of the most popular doublets to use. Peptide receptor radionuclide therapy was successfully implemented in patients with well-differentiated gastro-entero-pancreatic neuroendocrine tumours, but with certain questions waiting to be solved for the management of PanNETs. Finally, the role of immunotherapy is still poorly understood. In this review, the data supporting current systemic treatment options for locally advanced or metastatic PanNETs are summarized. Strategies for treatment selection in patients with PanNETs based on patient, disease, or drug characteristics is provided, as well as a summary of current evidence on prognostic and predictive biomarkers. Future perspectives are discussed, focusing on current and forthcoming challenges and unmet needs of patients with these rare tumours.

Somatostatinoma: Beyond neurofibromatosis type 1 (Review)

Somatostatinoma is a tumour mainly originating from pancreas or duodenum; overall with an incidence of 1/40 million persons. We introduce a narrative review of literature of somatostatinoma including the relationship with neurofibromatosis type 1. Clinical presentation includes: Diabetes mellitus, cholelithiasis, steatorrhea, abdominal pain, and obstructive jaundice while papillary tumour may cause acute pancreatitis. The neoplasia may develop completely asymptomatic or it is detected as an incidental finding during an imaging or a surgical procedure. It may be sporadic or associated to genetic backgrounds especially for duodenal localisation as neurofibromatosis type 1 (NF1 gene with malfunction of RAS/MAPK pathway) or Pacak-Zhuang syndrome (EPAS1 gene encoding HIF). Surgery represents the central approach if feasible but the prognostic depends on location, and grading as indicated by WHO 2017 classification of neuroendocrine tumours. Previously known as Von Recklinghausen disease, neurofibromatosis type 1, the most frequent neurocutaneous syndrome, is an autosomal dominant disorder including: Café-au-lait spot, skin fold freckling on flexural zones, and neurofibromas as well as tumours such as gliomas of optic nerve, gastrointestinal stromal tumours (GISTs), iris hamartomas and brain tumours. Duodenal somatostatinoma is associated with the syndrome which actually involves more often a duodenal tumour of GIST type than a somatostatin secreting neoplasia. Other neuroendocrine tumours are reported: Gastrointestinal NENs at the level of rectum or jejunum and pheocromocytoma. Overall, one quarter of subjects have gastrointestinal tumours of different types. Somatostatinoma, when not located on pancreas but in duodenoum, may be registered in subjects with neurofibromatosis type 1 most probably in addition to other tumours. Overall, this type of neuroendocrine tumour with a challenging presentation has a poor prognosis unless adequate radical surgery is promptly offered to the patient.

[Indications for the Surgical Management of Pancreatic Neuroendocrine Neoplasms]

Neuroendocrine neoplasms of the pancreas (pNEN) have an increasing incidence and prevalence. Thus, this entity is of increasing clinical significance. Patients with pNEN become clinically apparent due to different and unspecific symptoms. Some tumours secrete hormones and peptides and become clinically symptomatic. In general, these tumours can metastasise early and even small tumours lead to distant metastases. Nonetheless, primary tumour size and grading are important prognostic factors. On the basis of a systematic literature research and the formulation of key issues according to the PICO system, therapeutic concepts were established. These concepts were evaluated with a Delphi process among the members of the pancreas research group and the indications for surgery group of the German Society of General and Visceral Surgery. Thus this article gives an overview of the surgical treatment modalities and indications for the treatment of pNEN. Surgery is still the gold standard in treatment and the only potential chance of cure. Surgery is indicated for sporadic as well as hereditary pNEN > 2 cm independent of the functional activity. A so called "wait and see" strategy might be indicated in smaller pNEN; however, there is little evidence for this approach. In this respect, pNEN of 1 - 2 cm represent a surgical indication. The treatment of hereditary pNEN is challenging and should be interdisciplinary. Even in the case of distant metastases, a curative approach might be feasible and multimodal treatment is indicated.

Liver Tumor Burden in Pancreatic Neuroendocrine Tumors: CT Features and Texture Analysis in the Prediction of Tumor Grade and 18F-FDG Uptake

Pancreatic neuroendocrine tumors (p-NETs) are a rare group of neoplasms that often present with liver metastases. Histological characteristics, metabolic behavior, and liver tumor burden (LTB) are important prognostic factors. In this study, the usefulness of texture analysis of liver metastases in evaluating the biological aggressiveness of p-NETs was assessed. Fifty-six patients with liver metastases from p-NET were retrospectively enrolled. Qualitative and quantitative CT features of LTB were evaluated. Histogram-derived parameters of liver metastases were calculated and correlated with the tumor grade (G) and ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) standardized uptake value (SUV). Arterial relative enhancement was inversely related with G (−0.37, p = 0.006). Different metastatic spread patterns of LTB were not associated with histological grade. Arterial_entropy was significantly correlated to G (−0.368, p = 0.038) and to Ki67 percentage (−0.421, p = 0.018). The ROC curve for the Arterial_entropy reported an area under the curve (AUC) of 0.736 (95% confidence interval 0.545–0.928, p = 0.035) in the identification of G1–2 tumors. Arterial_uniformity values were correlated to G (0.346, p = 0.005) and Ki67 levels (0.383, p = 0.033). Arterial_entropy values were directly correlated with the SUV (0.449, p = 0.047) which was inversely correlated with Arterial_uniformity (−0.499, p = 0.025). Skewness and kurtosis reported no significant correlations. In conclusion, histogram-derived parameters may predict adverse histological features and metabolic behavior of p-NET liver metastases.

Biomarkers for Pancreatic Neuroendocrine Neoplasms (PanNENs) Management-An Updated Review

Pancreatic neuroendocrine tumors (PanNENs) are rare sporadic cancers or develop as part of hereditary syndromes. PanNENs can be both functioning and non-functioning based on whether they produce bioactive peptides. Some PanNENs are well differentiated while others-poorly. Symptoms, thus, depend on both oncological and hormonal causes. PanNEN diagnosis and treatment benefit from and in some instances are guided by biomarker monitoring. However, plasmatic monoanalytes are only suggestive of PanNEN pathological status and their positivity is typically followed by deepen diagnostic analyses through imaging techniques. There is a strong need for new biomarkers and follow-up modalities aimed to improve the outcome of PanNEN patients. Liquid biopsy follow-up, i.e., sequential analysis on tumor biomarkers in body fluids offers a great potential, that need to be substantiated by additional studies focusing on the specific markers and the timing of the analyses. This review provides the most updated panorama on PanNEN biomarkers.

Comparison between neuroendocrine carcinomas and well-differentiated neuroendocrine tumors of the pancreas using dynamic enhanced CT

OBJECTIVES

To identify CT features distinguishing neuroendocrine carcinomas (NECs) of pancreas from well-differentiated neuroendocrine tumors (NETs) according to the World Health Organization 2017 and 2019 classification systems.

METHODS

This retrospective study included 69 patients with pathologically confirmed pancreatic neuroendocrine neoplasms who underwent dynamic CT (17, 17, 18, and 17 patients for well-differentiated grade 1, 2, 3 NET and NEC, respectively). CT was used to perform qualitative analysis (component, homogeneity, calcification, peripancreatic infiltration, main pancreatic ductal dilatation, bile duct dilatation, intraductal extension, and vascular invasion) and quantitative analysis (interface between tumor and parenchyma [delta], arterial enhancement ratio [AER], portal enhancement ratio [PER], and dynamic enhancement pattern). Uni- and multivariate logistic regression analyses were performed to identify features indicating NEC. Optimal cutoff values for enhancement ratios were determined.

RESULTS

NECs demonstrated significantly higher frequencies of main pancreatic ductal dilatation, bile duct dilatation, vascular invasion, and significantly lower delta (i.e., lower conspicuity), AER, and PER than well-differentiated NET (p < 0.05). On multivariate analysis, PER was the only independent factor selected by the model for differentiation of NEC from well-differentiated NET (odds ratio, < 0.001; 95% confidence interval [CI], < 0.001-0.012). PER < 0.8 showed the sensitivity of 94.1% (95% CI, 71.3-99.9) and the specificity of 88.5% (95% CI, 76.6-95.6). When three significant CT features were combined, the sensitivity and specificity for diagnosing NEC were 88.2% and 88.5%, respectively.

CONCLUSIONS

Tumor-parenchyma enhancement ratio in portal phase is a useful CT feature to distinguish NECs from well-differentiated NETs. Combining qualitative and quantitative CT features may aid in achieving good diagnostic accuracy in the differentiation between NEC and well-differentiated NET.

KEY POINTS

• Neuroendocrine carcinoma of the pancreas should be distinguished from well-differentiated neuroendocrine tumor in line with the revised grading and staging system. • Neuroendocrine carcinoma of the pancreas can be differentiated from well-differentiated neuroendocrine tumor on dynamic CT based on assessment of the portal enhancement ratio, arterial enhancement ratio, tumor conspicuity, dilatation of the main pancreatic duct or bile duct, and vascular invasion. • Tumor-parenchyma enhancement ratio in portal phase of dynamic CT is a useful feature, which may help to distinguish neuroendocrine carcinoma from well-differentiated neuroendocrine tumor of the pancreas.

Differential and prognostic MRI features of gallbladder neuroendocrine tumors and adenocarcinomas

OBJECTIVES

To identify MRI features that are helpful for the differentiation of gallbladder neuroendocrine tumors (GB-NETs) from gallbladder adenocarcinomas (GB-ADCs) and to evaluate their prognostic values.

METHODS

Between January 2008 and December 2018, we retrospectively enrolled patients who underwent MRI for GB malignancy. Two radiologists independently assessed the MRI findings and reached a consensus. Significant MRI features, which distinguish GB-NETs from GB-ADCs, were identified. Cox regression analyses were performed to find MRI features that were prognostic for overall survival.

RESULTS

There were 63 patients with GB-NETs (n = 21) and GB-ADCs (n = 42). Compared with GB-ADCs, GB-NETs more frequently demonstrated the following MRI features: well-defined margins, intact overlying mucosa, and thick rim contrast enhancement and/or diffusion restriction (ps < 0.001). Liver metastases were more common and demonstrated thick rim contrast enhancement and diffusion restriction in GB-NETs (ps < 0.001). Lymph node (LN) metastasis showed thick rim diffusion restriction more often in GB-NETs than in GB-ADCs (p = 0.009). On quantitative analysis, the sizes of the GB mass and metastatic LNs in GB-NETs were larger than those in GB-ADCs (p = 0.002 and p = 0.010, respectively). The ratio of apparent diffusion coefficient values between the lesion and the spleen was lower in the GB mass, liver metastases, and LN metastases of GB-NETs than those of GB-ADCs (p < 0.001, p = 0.017, and p < 0.001, respectively). Survival analysis revealed that a large metastatic LN (hazard ratio 1.737; 95% confidence interval, 1.112-2.712) was the only poor prognostic factor (p = 0.015).

CONCLUSION

Several MRI features aided in differentiating between GB-NETs and GB-ADCs. A large metastatic LN was associated with poor survival.

KEY POINTS

• Compared with gallbladder adenocarcinomas (GB-ADCs), neuroendocrine tumors (GB-NETs) and their metastases to the liver and lymph nodes more frequently demonstrated a thick rim appearance on contrast-enhanced MRI and diffusion-weighted images. • The ratio of apparent diffusion coefficient values between the lesion and the spleen was significantly lower for the primary mass, liver metastases, and lymph node metastases of GB-NETs than for those of GB-ADCs. • A large metastatic lymph node was the only poor prognostic factor for overall survival in patients with GB-NETs and GB-ADCs.

Carcinoid Tumor: Advances in Treatment Options

Small bowel neoplasms are rare, accounting for only 3%-6% of all gastrointestinal neoplasms. Carcinoid tumors represent a large portion of these (20%-30%), making them the second most common small bowel malignancy after adenocarcinoma. Gastrointestinal carcinoids constitute 70% of all neuroendocrine tumors, and out of those, 42% originate in the small bowel. They are predominantly seen in older patients around the age of 65 years. From 1973 to 2004, there has been more than a fourfold increase in the incidence of carcinoid tumors. This can be probably due to increased diagnostic accuracy rather than an actual increase in the number of new cases. The workup of a suspicious case of gastrointestinal bleeding consists of esophagogastroduodenoscopy and/or colonoscopy, and other imaging tests including video capsule endoscopy and balloon-assisted endoscopy. Management of the tumors is dependent on the size and location of the lesion. Treatment options include surgery, endoscopic removal of tumors, and various immunotherapy and chemotherapeutic agents.