Mixed Neuroendocrine Non-Neuroendocrine Neoplasms: A Systematic Review of a Controversial and Underestimated Diagnosis

An Italian real-world multicenter study of patients with advanced mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) of the gastro-entero-pancreatic system treated with chemotherapy

PURPOSE

The aim of this study is to describe the clinical management of an Italian series of patients with advanced gastro-entero-pancreatic (GEP) MiNENs treated in clinical practice.

METHODS

Clinical records of patients from four Italian referral Centers were retrospectively analyzed to correlate clinical/biological data with clinical outcomes. All the surgical specimens were centrally reviewed.

RESULTS

Clinical data and surgical samples of 51 patients during 1995-2015 were analyzed. Sites of origin were: 32 colorectal, 14 gastro-esophageal, and 5 pancreatobiliary. Twenty-one out of fifty-one (42.2%) developed metachronous distant metastases. Only 5/51 (9.8%) patients received peri-operative therapy, and 23/51 (45.1%) first-line chemotherapy, mostly fluoropyrimidines/oxaliplatin. The NEN component was poorly differentiated in the whole population. Patients with Ki67 index < 55% in the NEC component had a significantly longer median overall survival (OS) (35.3 months; 95% CI 27.1-41.0) than those with Ki67 ≥ 55% (11.9 months; 95% CI 9.1-14.0) P = 0.0005. The median OS was 14 months (95% CI 10.1-19.1) in the whole cohort, with 11.4 months (95% CI 6.2-20.2) in patients who received a first-line therapy.

CONCLUSION

This study confirms that GEP-MiNENs represent a complex disease and that over the past years the clinical management has been predominantly guided by the subjective judgment of the clinicians. Although, in this series, the NEC component appeared mostly responsible for the systemic spread and prognosis on the whole neoplasm, the lack of strong prognostic and predictive factors universally recognized seems to condition their management so far. Future prospective clinical and biomolecular studies could help clinicians to improve clinical management of GEP-MiNENs.

Mixed Neuroendocrine-Squamous Cell Carcinoma of the Hand With Metastatic Dissemination: A Case Report

Cutaneous manifestations of mixed neuroendocrine non-neuroendocrine neoplasms remain a diagnostic rarity. Predominantly identified within internal glandular organs, the digestive tract, and in the hepatobiliary system, this case report illustrates a unique occurrence of a mixed squamous cell and neuroendocrine tumor in the index finger of a justice-affected patient. We discuss the complexities of diagnosis and complications as well as emphasize the importance for hand surgeons to recognize presentations like this and the need for vigilant follow-up and improved care coordination.

Does the size of the neuroendocrine-carcinoma component determine the prognosis of gallbladder cancer?

Background

Gallbladder mixed neuroendocrine-non-neuroendocrine neoplasm generally consists of a gallbladder neuroendocrine tumor and a non-neuroendocrine component. The World Health Organization (WHO) in 2019 established a guideline requiring each component, both neuroendocrine and non-neuroendocrine, to account for a minimum of 30% of the tumor mass.

Methods

Patients after surgery resection and diagnosed at microscopy evaluation with pure gallbladder neuroendocrine carcinoma (GBNEC), gallbladder mixed adeno-neuroendocrine carcinoma (GBMANEC, GBNEC≥30%), and gallbladder carcinoma mixed with a small fraction of GBNEC (GBNEC <30%) between 2010 and 2022 at West China Hospital of Sichuan University were collated for the analyses. Demographic features, surgical variables, and tumor characteristics were evaluated for association with patients' overall and recurrence-free survival (OS and RFS).

Results

The study included 26 GBNEC, 11 GBMANEC, 4 gallbladder squamous-cell carcinoma (GBSCC), and 7 gallbladder adenocarcinoma (GBADC) mixed with a small fraction of GBNEC. All patients had stage III or higher tumors (AJCC8th edition). The majority of included patients (79.17%) underwent curative surgical resection (R0), with only ten patients having tumoral resection margins. In the analysis comparing patients with GBNEC percentage (GBNEC≥30% vs. GBNEC<30%), the basic demographics and tumor characteristics of most patients were comparable. The prognosis of these patients was also comparable, with a median OS of 23.65 months versus 20.40 months (P=0.13) and a median RFS of 17.1 months versus 12.3 months (P=0.24). However, patients with GBADC or GBSCC mixed with GBNEC <30% had a statistically significant decreased OS and RFS (both P<0.0001)) compared with GBNEC and GBMANEC. Patients with GBNEC who exhibited advanced tumor stages and lymphovascular invasion had a higher risk of experiencing worse overall survival (OS) and recurrence-free survival (RFS). However, a 30% GBNEC component was not identified as an independent risk factor.

Conclusion

Patients with GBNEC were frequently diagnosed at advanced stages and their prognosis is poor. The 30% percentage of the GBNEC component is not related to the patient's survival.

Mixed neuroendocrine and adenocarcinoma of gastrointestinal tract: A complex diagnosis and therapeutic challenge

In this editorial we comment on the manuscript describing a case of adenocarcinoma mixed with a neuroendocrine carcinoma of the gastroesophageal junction. Mixed neuroendocrine and non-neuroendocrine neoplasms of the gastrointestinal system are rare heterogeneous group of tumors characterized by a high malignant potential, rapid growth, and poor prognosis. Due to the rarity of these cancers, the standard therapy is poorly defined. The diagnosis of these tumors is based on combination of morphological features, immunohistochemical and neuroendocrine and epithelial cell markers. Both endocrine and epithelial cell components can act independently of each other and thus, careful grading of each component separately is required. These cancers are aggressive in nature and the potential of each component has paramount importance in the choice of treatment and response. Regardless of the organ of origin, these tumors portend poor prognosis with increased proportion of neuroendocrine component. Multidisciplinary services and strategies are required for the management of these mixed malignancies to provide the best oncological outcomes. The etiopathogenesis of these mixed tumors remains obscure but poses interesting question. We briefly discuss a few salient points in this editorial.

Unveiling the Rarity: A Case of a Mixed Neuroendocrine-Non-Neuroendocrine Tumor of the Gastroesophageal Junction

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are a rare group of heterogeneous tumors, consisting of an endocrine and a nonendocrine component, which can develop throughout the gastrointestinal (GI) tract. This case presents a 70-year-old man with a complex medical history who initially presented with an upper GI bleed. After being stabilized, he underwent an esophagogastroduodenoscopy (EGD) that revealed a suspicious gastroesophageal junction (GEJ) mass. Histopathological studies paired with immunohistochemical investigations of the mass confirmed the rare diagnosis of MiNENs. He then underwent an endoscopic submucosal dissection (ESD) with subsequent chemotherapy and adjunct radiotherapy, with no recurrence noted on post-treatment surveillance. This case highlights the need for an EGD, histopathological examination, and immunohistochemical staining for detecting the underlying etiology of an upper GI bleed.

Mixed neuroendocrine non-neuroendocrine neoplasms in gastroenteropancreatic tract

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) are a heterogeneous group of malignant neoplasms that can settle in the gastroenteropancreatic tract. They are composed of a neuroendocrine (NE) and a non-NE component in at least 30% of each tumour. The non-NE component can include different histological combinations of glandular, squamous, mucinous and sarcomatoid phenotypes, and one or both of the components can be low-or high grade malignant. Recent changes in the nomenclature of these neoplasms might lead to great deal of confusion, and the lack of specific clinical trials is the main reason why their management is difficult. The review aims to clarify the definition of MiNEN and analyze available evidence about their diagnosis and treatment options according to their location and extension through careful analysis of the available data. It would be important to reach a general consensus on their diagnosis in order to construct a classification that remains stable over time and facilitates the design of clinical trials that, due to their low incidence, will require long recruitment periods.

Gastric mixed neuroendocrine non-neuroendocrine neoplasms

The uncommon tumour known as gastric mixed neuroendocrine-non-neuroendocrine neoplasms (G-MiNENs) is made up of parts of neuroendocrine carcinoma and adenocarcinoma. The biological and clinical features are different from those of gastric adenocarcinoma. Their pathophysiology, diagnostic standards, and clinical behaviour have all been the subject of lengthy debates, and their nomenclature has undergone multiple changes. Its emergence has created new challenges in the classification and diagnosis of gastric tumours. This review will update information on the topic, covering molecular aspects, diagnostic criteria, treatment, and prognostic factor discovery. It will also provide a historical context that will aid in understanding the evolution of the idea and nomenclature of mixed gastric tumours. Additionally, it will provide the reader a thorough understanding of this difficult topic of cancer that is applicable to real-world situations.

Primary Oral Mixed Neuroendocrine-Non-neuroendocrine Neoplasm (MiNEN): A Rare Case Report and Review of the Literature

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are rare tumors recently characterized by the presence of both neuroendocrine and non-neuroendocrine components within the same tumor tissue. Although MiNEN found their place in the WHO classification for various organs, this composite tumor in the head and neck region remains exceptionally rare. We present a case of primary oral MiNEN in a 64-year-old male located on the left side of lower gingiva. Biopsy raised suspicion of neuroendocrine carcinoma (NEC) and the patient underwent partial mandibulectomy. The resected specimen showed two distinct components of NEC and squamous cell carcinoma (SCC) with the confirmation of immunohistochemical markers. There has been no sign of recurrence nor metastasis 6 years after the surgery. In addition, we have conducted a review of published cases with potential relevance to this entity, resulting in five cases. The diverse terminology reinforces the need for a standardized classification system of oral/head and neck MiNENs.

Unexpected pancreatic mixed neuroendocrine-nonneuroendocrine neoplasms (MiNEN)-reflection on a case report

The authors present a case involving a 51-year-old male who was diagnosed with a 4-cm mass in the body of the pancreas, initially suspected to be a ductal adenocarcinoma due to an elevated Ca 19.9 during routine analysis. Subsequent imaging studies confirmed a resectable disease without suspicious lymph nodes or distant metastasis, leading to the proposal of surgery. The patient underwent a laparoscopic distal splenopancreatectomy, which was uneventful. The histopathological examination revealed a 3.7-cm pancreatic mixed neuroendocrine neoplasia (MiNEN) with a predominant high-grade ductal adenocarcinoma component and a concurrent high-grade neuroendocrine carcinoma, with negative margins. Two lymph node metastases were identified, each representing metastasis of one of the components. The tumor was classified as pT2N1M0. Currently, the patient is undergoing chemotherapy with FOLFIRINOX. This case prompts reflection on the optimal treatment strategy for pancreatic MiNEN and raises the question of how the preoperative diagnosis could influence the patient's outcome.

Mixed Neuroendocrine-Non-Neuroendocrine Neoplasms of the Rectum: A Case Report

Introduction

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) represent roughly 1-2% of all colorectal malignancies. Given the rareness and heterogeneity of these mixed tumors, recognition and accurate diagnosis remain a challenge. In the absence of established guidelines, they are treated according to the standard of care for pure neuroendocrine carcinomas or adenocarcinomas from similar sites of origin.

Case Presentation

We herein report a case of a rectal MiNEN in a 55-year-old male. He underwent colonoscopy for rectal bleeding and mucus emission, which revealed a vegetating lesion located approximately 8 cm from the anal verge, corresponding to a moderately differentiated low-grade adenocarcinoma of the rectum. Computed tomography scan and magnetic resonance imaging uncovered the presence of lung, lymph node, and subcutaneous implant metastases. The biopsy of the cutaneous implant showed neuroendocrine carcinoma Ki-67 90%. The patient underwent systemic chemotherapy.

Conclusion

High-grade MiNEN tumors are the most commonly encountered in clinical practice and have an aggressive biological behavior. Little is known about the genetic drivers of this neoplasm and its pathogenesis remains controversial. Clinical and pathological awareness of this rare entity is a key step to design future targeted therapies and improve treatment options. The aim of this case report is to further our understanding regarding the clinical presentation, radiological features, pathology, management, and prognosis of MiNEN.

Comparison of the clinical features and long-term prognosis of gallbladder neuroendocrine carcinoma versus gallbladder adenocarcinoma: A propensity score-matched analysis

Gallbladder neuroendocrine carcinoma (GBNEC) is rare and characterized by a low degree of tumor differentiation. The clinical features of GBNEC versus gallbladder adenocarcinoma (GBADC) remain a subject of debate. A total of 201 GBADC and 36 GBNEC cases that underwent surgery resection between January 2010 and 2022 at the Department of Biliary Surgery, West China Hospital, Sichuan University were included. A 1:1 propensity score matching (PSM) was performed based on seven predefined variables: age, sex, the American Joint Committee on Cancer (AJCC) stage, resection status, perineural invasion (PNI), lymphovascular invasion (LVI), and degree of tumor differentiation. Compared with GBADC, GBNEC patients were younger (median age 56.0 vs 64.0 years; P = 0.001), and more patients presented with advanced stages of tumor (P = 0.003). Patients with GBNEC also had a higher rate of PNI (55.6% vs 22.4%; P < 0.001), and LVI (63.9% vs 45.80%; P = 0.658). Before PSM, GBNEC patients had inferior prognoses compared with GBADC patients with a shorter median overall survival (mOS) (15.02 vs 20.11 months; P = 0.0028) and a shorter median recurrence-free survival (mRFS) (10.30 vs 15.17 months; P = 0.0028). However, after PSM analyses, there were no differences in OS (mOS 18.6 vs 18.0 months; P=0.24) or RFS (mRFS 10.98 vs 12.02 months; P = 0.39) between the GBNEC and GBADC cases. After multivariate analysis, tumor diagnosis (GBNEC vs GBADC) was not identified as an independent risk factor for shorter RFS (P = 0.506) or OS (P = 0.731). Unfavorable pathological features, including advanced AJCC tumor stages, poor differentiation, presence of LVI, and positive resection margins (all P < 0.05), were independent risk factors for inferior OS and RFS. GBNEC is difficult to diagnose early and has a prognosis comparable to stage-matched poorly differentiated GBADC. Tumor diagnosis (either GBADC or GBNEC) was not an independent risk factor for the patient's OS. Unfavorable pathological features of the neoplasm are the main determinants.

Incidence, survival, and prognostic factors for patients with gastrointestinal mixed neuroendocrine non-neuroendocrine neoplasms: a SEER population-based study

BACKGROUND

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) are a group of rare tumors with limited research currently available. This study aimed to analyze the incidence, survival, and prognostic factors of gastrointestinal MiNENs.

METHODS

We included data from the Surveillance, Epidemiology, and End Results (SEER) database between 2000 and 2019. We compared the clinicopathologic characteristics and survival rates between MiNENs and neuroendocrine tumors (NETs), and calculated the incidence of MiNENs. We utilized univariate and multivariate Cox analysis to assess independent factors of prognosis and established a nomogram to predict 1-, 2-, and 3-year cancer-specific survival (CSS). Calibration and receiver operating characteristic (ROC) curves were drawn to validate the accuracy and reliability of the model. Decision curve analysis (DCA) was used to assess the clinical utility of the model.

RESULTS

Patients with gastrointestinal MiNENs had a poorer prognosis than those with NETs. The overall incidence of gastrointestinal MiNENs has been increasing annually. Multivariate Cox regression analysis revealed that tumor size, lymph node metastasis, distant metastasis, and surgery were independent risk factors for CSS in MiNENs patients. Based on these risk factors, the 1-, 2-, and 3-year CSS nomogram model for MiNENs patients was established. Calibration, ROC, and DCA curves of the training and validation sets demonstrated that this model had good accuracy and clinical utility.

CONCLUSION

Gastrointestinal MiNENs are rare tumors with an increasing incidence rate. The nomogram model is expected to be an effective tool for personalized prognosis prediction in MiNENs patients, which may benefit clinical decision-making.

Progress in immunotherapy for neuroendocrine neoplasm of the digestive system

Neuroendocrine neoplasms (NENs) are rare heterogeneous tumors that can develop in almost any organ, with the digestive organs, including the gastrointestinal tract and pancreas being the most commonly affected sites. Despite the fact that advances in initial therapies have progressed, there is presently no recognized effective treatment for advanced NEN. Immune checkpoint inhibitors (ICIs) have shown superior efficacy in treating several types of solid tumors. Despite their successful role in the treatment of partial NENs, such as small cell lung cancer, and Merkel cell carcinoma, the role of ICIs in most of the NENs remains limited. Nevertheless, due to their specific anti-tumor mechanisms and acceptable safety profile, ICIs are a promising avenue for further study in NENs therapy. Recent clinical trials have illustrated that combination therapy with ICI is more efficient than monotherapy, and multiple clinical trials are constantly ongoing to evaluate the efficacy and safety of these combination therapies. Therefore, the purpose of this review is to provide a comprehensive summary of the clinical progress of immunotherapy in NENs affecting the digestive system, with a specific emphasis on the application of programmed cell death protein 1/programmed death receptor ligand 1 inhibitor. Furthermore, this review has an exploration of the potential beneficiary population and the inherent value of utilizing immunotherapy in the management of NENs.

Precise microdissection of gastric mixed adeno-neuroendocrine carcinoma dissects its genomic landscape and evolutionary clonal origins

Gastric mixed adenoneuroendocrine carcinoma (MANEC) is a clinically aggressive and heterogeneous tumor composed of adenocarcinoma (ACA) and neuroendocrine carcinoma (NEC). The genomic properties and evolutionary clonal origins of MANEC remain unclear. We conduct whole-exome and multiregional sequencing on 101 samples from 33 patients to elucidate their evolutionary paths. We identify four significantly mutated genes, TP53, RB1, APC, and CTNNB1. MANEC resembles chromosomal instability stomach adenocarcinoma in that whole-genome doubling in MANEC is predominant and occurs earlier than most copy-number losses. All tumors are of monoclonal origin, and NEC components show more aggressive genomic properties than their ACA counterparts. The phylogenetic trees show two tumor divergence patterns, including sequential and parallel divergence. Furthermore, ACA-to-NEC rather than NEC-to-ACA transition is confirmed by immunohistochemistry on 6 biomarkers in ACA- and NEC-dominant regions. These results provide insights into the clonal origin and tumor differentiation of MANEC.

Digestive MiNENs: Could histological classification and molecular characterization drive clinical outcome and therapeutic approach?

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are epithelial neoplasms in which neuroendocrine and non-neuroendocrine discrete components are combined, each of which constitutes ≥ 30% of the neoplasm. The finding of an additional neuroendocrine component seems to characterize the tumor's biological behavior. Few studies have proved MiNENs histogenetic and molecular characterization, and the development of molecular markers for more accurate classification of MiNENs represents a clinical need. However, a common origin of the neuroendocrine and non-neuroendocrine components from a pluripotent cancer stem cell could be suggested. The optimal clinical management of MiNENS is largely unknown. Whenever feasible, curative-intent resection should be performed for localized disease; in advanced disease, the treatment should be targeted to the component responsible for the metastatic spreading. This paper provides a revision of the current knowledge on MiNENs, focusing on available evidence about their molecular characterization to suggest a prognostic stratification of these rare forms.

Small Cell Carcinoma of the Gallbladder

Primary neuroendocrine carcinoma of the gallbladder (GB) is a rare, highly dismal lethal disease with a fatal prognosis. A 45-year-old female presented with right upper abdomen pain and multiple vomiting episodes. Imaging studies showed diffuse thickening of the wall of the GB with locoregional invasion into the nearby structures with extensive abdominal lymph node metastasis and arteriovenous encasements. Ultrasound-guided fine-needle aspiration was done, which was diagnostic of small cell carcinoma of the GB. The patient was planned for palliative chemotherapy. A small cell variant of neuroendocrine carcinoma of the GB is a rare entity with a moribund lethality associated with it. Patients are diagnosed in advanced stages with not many treatment modalities to offer. Usually, patients are treated with palliative chemotherapy.

An Unusual Case of Large Cell Neuroendocrine Cancer of the Gallbladder With Mixed Adenocarcinoma Component in a Patient With Pancreatobiliary Maljunction

Gallbladder neuroendocrine tumors (GB-NETs) and gallbladder neuroendocrine carcinomas (GB-NECs) are rare forms of neuroendocrine neoplasms (NENs). Most GB-NENs present as incidental findings or as gallbladder polyps in the course of investigation of nonspecific symptoms such as upper abdominal pain and nausea. Given the rarity of GB-NENs, only a few small case series are currently available describing this entity, and even fewer guiding consensus on standard treatment and the role of adjuvant therapy.  We present the case of a 65-year-old South American female referred for a chronic history of intermittent post-prandial epigastric pain, bloating, nausea, and occasional diarrhea. Pancreaticobiliary maljunction with dilation was present and she was diagnosed with primary gallbladder large cell neuroendocrine carcinoma (GB-LCNEC) mixed with a minor component of gallbladder adenocarcinoma.

Clinicopathological characteristics of mixed neuroendocrine-non-neuroendocrine neoplasms in gastrointestinal tract

BACKGROUND

In 2019, the World Health Organization (WHO) classification system updated the definition of mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs), previously known as mixed adenoneuroendocrine carcinomas (MANECs). The clinicopathological characteristics of this new definition remains to be clarified.

METHODS

We analyzed the clinical data of 43 patients diagnosed with MiNENs in Wuhan Union Hospital from 2011 to 2020 according to the definition of MiNENs proposed in 2019.

RESULTS

Among the 43 patients with MiNENs, the top two most common sites were stomach and colon, and 69.8% were males. Nearly half (21/43) of the patients were diagnosed at TNM stage III, and about 53.5% (23/43) of patients were the neuroendocrine neoplasm dominant type. Among the non-neuroendocrine tumor components of 43 MiNENs patients, adenocarcinoma accounted for 95.3% (41/43) and squamous cell carcinoma accounted for 4.7% (2/43)；95.3% (41/43) of the neuroendocrine neoplasm components were neuroendocrine carcinoma (NEC) and 4.7% (2/43) were neuroendocrine tumor (NET). Approximately 60.5% (26/43) neuroendocrine components had a Ki-67 index ≥ 55%. In addition, we further compared the prognosis of different subtypes of the MiNENs based on the neuroendocrine neoplasm component and non-neuroendocrine neoplasm component, and the results showed that there was no significant difference in survival between different subtypes of MiNENs (P > 0.05).

CONCLUSIONS

MiNENs can exhibit diverse clinicopathological characteristics, and there is no significant difference in prognosis among MiNENs subtypes, indicating that the definition of MiNENs can well summarize the prognosis of this type of tumor.

Unusual Microsatellite-Instable Mixed Neuroendocrine and Non-neuroendocrine Neoplasm: A Clinicopathological Inspection and Literature Review

BACKGROUND

Mixed neuroendocrine and non-endocrine neoplasms (MiNENs) are challenging to diagnose and manage clinically. The current understanding of MiNENs' pathobiology, molecular mechanisms, and management is incomplete. Though microsatellite instability (MSI) is known to impact carcinogenesis, reports examining MSI mechanisms for MiNENs are rare.

METHODS

We report an unusual colonic MSI-MiNEN uncovered in an 89-year-old woman and the review of the literature.

RESULTS

Pathologic inspection revealed a high-grade carcinoma composed of tumor cells with neuroendocrine histologic traits and immunophenotype intermixed with mucin-containing signet ring-like cells arranged in nested and micronodular patterns. Loss of MLH1 and PMS2 mismatch repair proteins was detected in tumor cells. INSM1 immunostaining highlighted about 50% of the tumour, further reinforcing the MiNEN diagnosis. Next-generation sequencing identified multiple carcinogenic mutations. Because of the advanced stage of the tumor and its adhesion to the adjacent organs, surgical resection was aborted; immunotherapy was initiated. The tumor is in remission 30 months following initiation of treatment, and the patient remains asymptomatic.

CONCLUSION

This unique MSI MiNEN was characterized by its immunohistochemical and molecular signatures and illustrated how correctly diagnosing MSI can strongly improve a patient's outcomes.

CT and MR imaging features of mixed neuroendocrine-non-neuroendocrine neoplasm of the pancreas compared with pancreatic ductal adenocarcinoma and neuroendocrine tumor

OBJECTIVE

This study aimed to assess the computed tomography (CT) and magnetic resonance imaging (MRI) features of pancreatic mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) and compare them with those of pancreatic ductal adenocarcinoma (PDAC) and neuroendocrine tumor (NET).

METHODS

Twelve patients with pancreatic MiNEN, 24 patients with PDAC, and 24 patients with NET, who underwent both contrast-enhanced CT and MRI, were included. Clinical data and the key imaging features were retrospectively evaluated by two independent readers and compared between MiNEN and PDAC or NET. Univariate and multivariable logistic regression analyses were performed to obtain predictors for pancreatic MiNEN.

RESULTS

Patients with pancreatic MiNEN more frequently presented with large size and heterogeneous and cystic components compared with PDAC (p < 0.031) and ill-defined irregular margins, progressive enhancement, and adjacent organ involvement compared with NET (p < 0.036). However, vascular invasion was less commonly seen in MiNEN than PDAC (p = 0.010). Moderate enhancement was observed more frequently in MiNEN than in PDAC or NET (p < 0.001). Multivariate logistic analyses demonstrated that moderate enhancement and ill-defined irregular margin were the most valuable features for the prediction of pancreatic MiNEN (p ≤ 0.044). The combination of the two features resulted in a specificity of 93.8%, sensitivity of 83.3%, and accuracy of 91.7%.

CONCLUSIONS

We have mainly described the radiological findings of pancreatic MiNEN with ill-defined irregular margin and moderate enhancement compared with PDAC and NET. The combination of imaging features could improve diagnostic efficiency and help in the selection of the correct treatment method.

Comprehensive analysis of mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs): A SEER database analysis of 767 cases

Background

Mixed neuroendocrine non-neuroendocrine neoplasm (MiNEN) is an extremely rare entity, consisting of neuroendocrine and non-neuroendocrine components. It can occur in various organs throughout the body, with a rising incidence. Its clinical management is a rapidly growing field of interest; however, large-scale patient cohorts are still missing to guide clinical practice.

Patients and methods

The demographic, clinicopathological, and survival information of all patients diagnosed with MiNEN in the national Surveillance, Epidemiology, and End Results (SEER) program database (2000-2017) were extracted and further analyzed. The information of the patients before and after 2010 was compared to understand the epidemiological changes of MiNEN. The characteristics of MiNEN originating in different organs were compared. The clinical significance of surgical resection for metastatic MiNENs was also analyzed.

Results

A total of 1081 patients were screened, and after applying the exclusion criteria, 767 patients were finally analyzed. There was no obvious sex preference (49.2% vs 50.8%, p>0.05) and the majority of the patients were Caucasians (n=627, 81.7%). A total of 88.3% of the patients were older than 50 years old, and the median age was 60 years. 79.3% of the tumors are located in the distal digestive tract, and 67.7% were grade 3/4. Distant metastasis was presented in 33.9% of the patients at diagnosis. A total of 88% of the patients underwent surgical treatments. The number of patients increased 10-fold between 2000 and 2017. There was no significant difference in sex, race, stage, or surgical treatments among the patients diagnosed before and after 2010. More patients older than 60 years were diagnosed after 2010 (p=0.009). The median survival was 61.0 ± 9.8 months for the whole cohort. After multivariate analysis, older age (>60 years, p<0.01), more advanced stage (p<0.01), grade 3/4 (p<0.01), and non-surgical treatment (p<0.01) were independent risk factors for poorer survival. The appendiceal MiNENs showed the best prognosis. A total of 260 metastatic MiNENs were further analyzed. Only patients with metastatic MiNENs originating from the appendix had a potential benefit from surgical resection, compared to other sites (p=0.05).

Conclusion

This study provides the epidemiological, clinicopathological, and survival information of the largest number of MiNEN patients. Although MiNEN is an extremely rare malignant neoplasm, its incidence increases rapidly. The majority of the patients suffered from advanced-stage disease, which highlights the need for improvement of early detection in the future. The appendix is the most common primary site of MiNEN, and surgical resection for selected metastatic MiNEN originating in the appendix has favorable survival outcomes.

Deficient Mismatch Repair Proteins in Gastric Mixed Neuroendocrine Non-Neuroendocrine Neoplasm: A Rare Case Report

Mixed neuroendocrine non-neuroendocrine neoplasm (MiNEN) is a rare type of gastric carcinoma with controversial diagnosis and treatment. Recent data implies that deficiency mismatch repair proteins inducing microsatellite instability are considered one of the potential drivers of this disease. Hence, we report a stomach MiNEN with MMR protein loss. An admitted 60-year-old woman complained of epigastric pain. The pathological analysis of the gastro-endoscopic biopsy specimen revealed gastric adenocarcinoma. The radiological staging was cT3N1M0; therefore, she received D2 distal gastrectomy. Suspecting neuroendocrine component admix with adenocarcinoma part on the resected specimen microscopy, applying biomarkers including AE 1/3, synaptophysin, and chromogranin A to confirm the diagnosis of MiNEN. The neuroendocrine part was classified as neuroendocrine tumor grade 2 with Ki 67 at 16.5%. To further understand the molecular characterization of this disease, we evaluated mismatch protein expression by staining MLH1, MSH2, MSH6, and PMS2 antibodies. Interestingly, both components lost MLH1 and PMS2 proteins. Her radical surgery followed oxaliplatin/capecitabine adjuvant chemotherapy. The patient is still well after eight cycles of chemotherapy. dMMR gastric MiNENs and dMMR gastric cancer share many clinical and genetic characteristics. Further studies are necessary to survey the role of dMMR in the prognosis and treatment of this entity.

Survival in patients with neuroendocrine tumors of the colon, rectum and small intestine

BACKGROUND

Neuroendocrine neoplasms (NENs) of the colon, rectum and small intestine (SI) are increasing in incidence and prevalence. We evaluated the 5-year overall survival (OS), and cancer-specific survival (CSS).

METHODS

The Surveillance, Epidemiology, and End Results (SEER) 18 registry from 2000 to 2017 was accessed to identify patients with colonic, rectal, and SI NENs.

RESULTS

46,665 patients were diagnosed with NENs of the colon (n = 10,518, 22.5%), rectum (18,063, 38.7%), and SI (18,084, 38.8%). By tumor site alone, patients with well-differentiated neuroendocrine tumors (NETs) of the rectum had improved 5-year OS (HR 0.72, 95% CI 0.68-0.77, p < 0.001). However, patients with rectal poorly-differentiated neuroendocrine carcinomas (NECs) who underwent oncologic resection had lower 5-year OS (35.1%) compared to colon (41.9%), and SI (72.5%).

CONCLUSIONS

Surgical resection may improve 5-year OS for NECs of the SI and colon, except in the rectum where survival was reduced. More frequent surveillance and timely initiation of systemic therapy should be considered for rectal NECs.

Genomic characterization reveals distinct mutation landscapes and therapeutic implications in neuroendocrine carcinomas of the gastrointestinal tract

BACKGROUND

Neuroendocrine carcinomas of the gastrointestinal tract (GI-NECs) remain a disease of grim prognosis with limited therapeutic options. Their molecular characteristics are still undefined. This study aimed to explore the underlying genetic basis and heterogeneity of GI-NECs.

METHODS

Comprehensive genomic analysis using whole-exome sequencing was performed on 143 formalin-fixed, paraffin-embedded samples of surgically resected GI-NEC with a thorough histological evaluation. Mutational signatures, somatic mutations, and copy number aberrations were analyzed and compared across anatomic locations and histological subtypes. Survival analysis was conducted to identify the independent factors.

RESULTS

In total, 143 GI-NECs were examined: the stomach, 87 cases (60.8%); the esophagus, 29 cases (20.3%); the colorectum, 20 cases (14.0%); and the small intestine, 7 cases (4.9%). Eighty-three (58.0%) and 60 (42.0%) cases were subclassified into small cell and large cell subtypes, respectively. GI-NECs showed distinct genetic alterations from their lung counterparts and non-neuroendocrine carcinomas in the same locations. Obvious heterogeneity of mutational signatures, somatic mutations, and copy number variations was revealed across anatomic locations rather than histological subtypes. Except for tumor protein p53 (TP53) and retinoblastoma 1 (RB1), the most frequently mutated genes in the stomach, esophagus, colorectum, and small intestine were low-density lipoprotein receptor-related protein 1B (LRP1B), notch receptor 1 (NOTCH1), adenomatosis polyposis coli (APC), catenin beta 1 (CTNNB1), respectively. Mutations in the WNT-β-catenin, NOTCH and erythroblastic leukemia viral oncogene B (ERBB) pathways were prevalently identified in gastric, esophageal, and colorectal NECs, respectively. Importantly, 104 (72.7%) GI-NECs harbored putative clinically relevant alterations, and non-gastric location and RB1 bi-allelic inactivation with copy number alterations were identified as two independent poor prognostic factors. Furthermore, we found that tumor cells in GI-NECs first gain clonal mutations in TP53, RB1, NOTCH1 and APC, followed by subsequent whole-genome doubling (WGD) and post-WGD clonal mutations in LRP1B, CUB and Sushi multiple domains 3 (CSMD3), FAT tumor suppressor homolog 4 (FAT4) and erb-b2 receptor tyrosine kinase 4 (ERBB4), and finally develop subclonal mutations.

CONCLUSIONS

GI-NECs harbor distinct genomic landscapes and demonstrate significant genetic heterogeneity across different anatomic locations. Moreover, potentially actionable alterations and prognostic factors were revealed for GI-NECs.

From morphology to molecular targets—the pathologist’s view in diagnosing gastroenteropancreatic neuroendocrine neoplasms

In the last decade, a number of genetic alterations in gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) have been identified. In addition, differences in tumor morphology as well as proliferation index (Ki-67) or number of mitoses have led to changes in the classification of these neoplasms. According to the new World Health Organization (WHO) classification, GEP-NENs are now divided into two genetically and prognostically different categories: (i) well-differentiated neuroendocrine tumors (NET) subdivided into low (G1), intermediate (2) and high (G3) grade tumors, and (ii) poorly differentiated neuroendocrine carcinomas (NEC). In addition, a group of mixed neuroendocrine–non-neuroendocrine neoplasms (MiNEN) has been defined. This review focuses on the clinical, morphological, immunohistochemical and molecular findings of the GEP-NENs and their key diagnostic features that can help the pathologist to differentiate between tumors in this heterogeneous group. In challenging cases, additional immunohistochemical and/or molecular analysis can be helpful to determine the correct diagnosis and proper treatment for the patient.

DLL3 as an Emerging Target for the Treatment of Neuroendocrine Neoplasms

INTRODUCTION

Neuroendocrine neoplasms (NEN) are heterogeneous malignancies that can arise at almost any anatomical site and are classified as biologically distinct well-differentiated neuroendocrine tumors (NET) and poorly differentiated neuroendocrine carcinomas (NEC). Current systemic therapies for advanced disease, including targeted therapies, chemotherapy, and immunotherapy, are associated with limited duration of response. New therapeutic targets are needed. One promising target is delta-like ligand 3 (DLL3), an inhibitory ligand of the Notch receptor whose overexpression on the surface of NEN is associated with tumorigenesis.

METHODS

This article is a narrative review that highlights the role of DLL3 in NEN progression and prognosis, the potential for therapeutic targeting of DLL3, and ongoing studies of DLL3-targeting therapies. Classification, incidence, pathogenesis, and current management of NEN are reviewed to provide biological context and illustrate the unmet clinical needs.

DISCUSSION

DLL3 is overexpressed in many NENs, implicated in tumor progression, and is typically associated with poor clinical outcomes, particularly in patients with NEC. Targeted therapies using DLL3 as a homing beacon for cytotoxic activity mediated via several different mechanisms (eg, antibody-drug conjugates, T-cell engager molecules, CAR-Ts) have shown promising clinical activity in small-cell lung cancer (SCLC). DLL3 may be a clinically actionable target across NEN.

CONCLUSIONS

Current treatment options for NEN do not provide sustained responses. DLL3 is expressed on the cell surface of many NEN types and is associated with poor clinical outcomes. Initial clinical studies targeting DLL3 therapeutically in SCLC have been promising, and additional studies are expanding this approach to the broader group of NEN.

Pancreatic mixed acinar-neuroendocrine carcinoma in a patient with a germline BRCA2 mutation: a case report

Loss of function in the BRCA2 gene exacerbates ovarian, breast, and pancreatic ductal cancer risk. Despite being implicated in the pancreatic ductal epithelium carcinogenesis, the involvement of a germline BRCA2 mutation in acinar and endocrine cells is less reported. A 45-year-old woman with a history of breast cancer was referred to our hospital for a detailed examination of epigastric pain. Her father had pancreatic cancer, and her paternal aunt had a history of breast cancer. Contrast-enhanced computed tomography revealed a round tumor with a contrast effect in the pancreatic head. The patient underwent pancreaticoduodenectomy, and postoperative pathology and genetic testing revealed amphicrine-type mixed acinar-neuroendocrine carcinoma with a germline BRCA2 mutation. Recent studies have reported the BRCA2 mutation in genome sequencing of pancreatic acinar cell carcinoma and neuroendocrine tumor; perhaps, genetic testing for the BRCA2 mutation is feasible for patients with mixed neuroendocrine-non-neuroendocrine neoplasm.

Intra-ampullary papillary-tubular neoplasm combined with ampullary neuroendocrine carcinoma: A case report

BACKGROUND

The ampulla of Vater is an anatomically and histologically complex region giving rise to a heterogenous group of tumors. This is, to the best of our knowledge, the first case of intra-ampullary papillary-tubular neoplasm combined with ampullary neuroendocrine carcinoma reported in the literature.

CASE SUMMARY

A 61-year-old woman presented to the emergency department for evaluation of painless jaundice. Contrast-enhanced computed tomography (CT) of the abdomen and chest showed a periampullary tumor mass measuring 15 mm × 12 mm × 14 mm, with no evidence of locoregional and distant metastases, for which she underwent pancreatoduodenectomy. Histopathologic examination of a resected specimen revealed an intra-ampullary papillary tubular neoplasm with high-grade dysplasia in combination with poorly differentiated grade 3 neuroendocrine carcinoma with a mitotic count of more than 20 mitoses per 10 high power fields and Ki-67 index of 100%. No positive lymph nodes were identified. Her postoperative course was uneventful. Postoperatively, she remained under close surveillance. Multiple liver metastases were observed on follow-up CT 8 mo after the surgery, so systemic therapy with cisplatin and etoposide was initiated.

CONCLUSION

The simultaneous occurrence of neuroendocrine and non-neuroendocrine tumors in the ampulla of Vater is rare and the pathogenesis of such tumors is largely unknown. Due to unpredictable clinical behavior and lack of solid evidence on optimal treatment strategy, close patient surveillance is advised after radical resection of the primary tumor.

Mixed neuroendocrine-non-neuroendocrine neoplasm of the gallbladder: case report and literature review

Background

Mixed neuroendocrine–non-neuroendocrine neoplasms (MiNENs) of the gallbladder are rare malignancies. Here we presented two cases and reviewed the related literature.

Case presentation

Our two patients were postoperatively diagnosed with gallbladder MiNENs, which pathologically consisted of a large cell neuroendocrine carcinoma and papillary adenocarcinoma. After cholecystectomy, one patient had a survival time of 30 months, while the other remained alive through 12 months of follow-up. In the literature, a total of 72 cases of gallbladder MiNENs were identified, and with our two patients included, we calculated a male-to-female ratio of 0.22 and a mean age of 64.5 years for the 74 reported cases. About one-half of these patients were found to have gallstones and presented with abdominal pain or discomfort in a relatively early stage. The preoperative diagnosis of these 74 cases mainly relied on abdominal ultrasound, contrast-enhanced computed tomography (CT) scanning, and magnetic resonance imaging or positron emission tomography/CT. However, the final diagnosis was established based upon the pathological evidence and expression of synaptophysin (Syn) and/or chromogranin A identified by immunohistochemical staining or neurosecretory granules detected by electron microscopy. Fifty-eight patients (78.4%) underwent various operations including simple cholecystectomy (n = 14), en bloc cholecystectomy (n = 9), standard or non-standard radical cholecystectomy (n = 25), or extended radical cholecystectomy (n = 6). The mean size of the resected gallbladder masses was 50.8 ± 36.1 mm (n = 63) with regional lymph node metastasis in 37 patients (52.1%), liver invasion or staging greater than T3 in 33 patients (45.8%), and hepatic metastasis in 26 patients (35.1%). The postoperative median survival time was 36 ± 11.42 months (95% confidence interval, 13.62 to 58.38 months). The log-rank analysis did not find that postoperative adjuvant chemotherapy contributed to a longer survival time relative to that among the patients who did not receive chemotherapy (numbers of patients, 15 versus 43; survival times, 36 months versus 30 months, p > 0.05).

Conclusions

Our two cases and the cases in the literature suggest that MiNENs of the gallbladder predominantly occur in women; are associated with early lymph node metastasis, local hepatic invasion, and hepatic metastasis; and can be managed by various surgeries as well as chemotherapy combined with somatostatin analogs.

Mixed neuroendocrine-non-neuroendocrine neoplasms of the digestive system: A mini-review

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are rare mixed tumors containing both neuroendocrine (NE) and non-NE components. Each component must occupy at least 30% of the tumor volume by definition. Recent molecular evidence suggests MiNENs are clonal neoplasms and potentially harbor targetable mutations similar to conventional carcinomas. There have been multiple changes in the nomenclature and classification of MiNENs which has created some confusion among pathologists on how to integrate the contributions of each component in a MiNEN, an issue which in turn has resulted in confusion in communication with front-line treating oncologists. This mini review summarizes our current understanding of MiNENs and outline diagnosis, prognosis, and management of these neoplasms. The authors emphasize the importance of treating the most aggressive component of the tumor regardless of its percentage volume.

Mixed Neuroendocrine Non-Neuroendocrine Neoplasms of the Gastrointestinal Tract: A Case Series

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) refer to heterogenous rare neoplasms constituted of at least a neuroendocrine population—either well-differentiated, or more frequently poorly differentiated—and a non-neuroendocrine population, both accounting for at least 30% of the whole tumor mass. Several studies recently focused on the key genetic and epigenetic changes underlying MiNENs to better understand how they develop, and explore biological similarities among the two components and their pure counterparts. However, their molecular landscape still remains poorly understood. NGS may represent a useful tool to study this orphan disease by detecting the main genetic alterations and possible therapeutic targets. NGS analysis on tissue and/or blood samples through the Foundation One (F1) platform was performed on consecutive samples collected from four patients diagnosed with MiNENs of the gastroenteric tract. Several genetic alterations were shared among samples from the same patients, thus suggesting a common origin between them, although morphology sometimes changed at histopathological evaluation. Common molecular alterations among samples from different patients that had not been previously described to our knowledge were also detected. Finally, it is of the utmost importance to clarify if the maintenance of the 30% cut-off is still essential in defining MiNENs and really manages to include all of the mixed neoplasms.

An update on the development of concepts, diagnostic criteria, and challenging issues for neuroendocrine neoplasms across different digestive organs

Digestive neuroendocrine neoplasms (NENs) are a group of heterogeneous neoplasms found throughout the digestive tract, with different behaviour and genetic background. In the last few years, nomenclature and WHO/UICC classifications of digestive NENs have changed, and molecular classifications have emerged, especially in pancreatic locations. Increasing patho-molecular details are needed to diagnose the different categories of NEN, including the use of helpful immunohistochemical markers. In this review, we address these topics in three successive chapters. We first briefly review recent updates in classifications, discuss important grading and proliferating issues and advances in the molecular understanding of NEN. Then, we provide an update on diagnosis, including the most important differential diagnoses of NEN, with a focus on high-grade neoplasms and mixed tumours. Finally, we highlight a variety of currently used and next-generation predictive and prognostic biomarkers as well as biomarkers of tumour origin and describe some site specificities of gastrointestinal NEN. We specifically focus on biomarkers available to pathologists with the potential to change the way patients with NEN are diagnosed and treated.

Mixed neuroendocrine-nonneuroendocrine neoplasm of the ampulla: Four case reports

BACKGROUND

Mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN) is a rare tumor that occurs in the gastrointestinal tract and pancreas, usually composed of adenocarcinoma and neuroendocrine carcinoma. MiNEN occurring in ampulla is even rarer. We report 4 cases of MiNEN in ampulla, combined with literature review to summarize the clinical features and treatment of the disease, in order to improve the understanding of the disease.

CASE SUMMARY

A retrospective analysis was performed in 4 cases of MiNEN of the ampulla diagnosed by pathology from 2014 to 2021. The 4 patients were all male, aged 67-81 years (average 72.25 years). Among them, 2 patients had jaundice, 1 patient had abdominal pain, and 1 patient had jaundice with abdominal pain as the first symptom. All 4 patients underwent enhanced CT or MRI, which all indicated that the tumors were located in the ampulla. Two patients underwent duodenoscopy, and a biopsy revealed ampullary adenocarcinoma. All 4 patients underwent radical pancreaticoduodenectomy. Four cases were followed up: One patient developed severe complications after the operation, his condition deteriorated, and he survived for 1 mo. In the other 3 patients, tumor recurrence was observed during follow-up, and 2 of them survived for 29 mo and 22 mo respectively. One case survived and is still being followed up.

CONCLUSION

MiNEN of the ampulla are extremely rare, lacking typical clinical symptoms and imaging features, and are usually diagnosed after postoperative histopathological and immunohistochemical examinations. The main treatment is radical surgical resection, which can be combined with chemotherapy. The best method of diagnosis and treatment needs further research.

Pancreatic Neuroendocrine Neoplasms: Updates on Genomic Changes in Inherited Tumour Syndromes and Sporadic Tumours Based on WHO Classification

Pancreatic neuroendocrine neoplasms (PanNENs) are the neuroendocrine neoplasms with greatest rate of increase in incidence. Approximately 10% of PanNENs arise as inherited tumour syndromes which include multiple endocrine neoplasia type 1, multiple endocrine neoplasia type 4, von Hippel-Lindau syndrome, neurofibromatosis type1, tuberous sclerosis complex 1/2, Cowden syndrome, and Glucagon cell hyperplasia and neoplasia as well as familial insulinomatosis. In sporadic PanNENs, driver mutations in MEN1, DAXX/ATRX and mTOR pathway genes are associated with development and progression in pancreatic neuroendocrine tumours. The other changes are in VEGF pathway, Notch pathway, germline mutations in MUTYH, CHEK2, BRCA2, PHLDA3 as well as other genetic alterations. On the other hand, pancreatic neuroendocrine carcinomas share similar genetic alterations with ductal adenocarcinomas, e.g., TP53, RB1 or KRAS. In addition, microRNA and changes in immune microenvironment were noted in PanNENs. Updates on these genetic knowledges contribute to the development of management strategies for patients with PanNENs.

Overview of the 2022 WHO Classification of Neuroendocrine Neoplasms

In this review, we detail the changes and the relevant features that are applied to neuroendocrine neoplasms (NENs) in the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors. Using a question-and-answer approach, we discuss the consolidation of the nomenclature that distinguishes neuronal paragangliomas from epithelial neoplasms, which are divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). The criteria for these distinctions based on differentiation are outlined. NETs are generally (but not always) graded as G1, G2, and G3 based on proliferation, whereas NECs are by definition high grade; the importance of Ki67 as a tool for classification and grading is emphasized. The clinical relevance of proper classification is explained, and the importance of hormonal function is examined, including eutopic and ectopic hormone production. The tools available to pathologists for accurate classification include the conventional biomarkers of neuroendocrine lineage and differentiation, INSM1, synaptophysin, chromogranins, and somatostatin receptors (SSTRs), but also include transcription factors that can identify the site of origin of a metastatic lesion of unknown primary site, as well as hormones, enzymes, and keratins that play a role in functional and structural correlation. The recognition of highly proliferative, well-differentiated NETs has resulted in the need for biomarkers that can distinguish these G3 NETs from NECs, including stains to determine expression of SSTRs and those that can indicate the unique molecular pathogenetic alterations that underlie the distinction, for example, global loss of RB and aberrant p53 in pancreatic NECs compared with loss of ATRX, DAXX, and menin in pancreatic NETs. Other differential diagnoses are discussed with recommendations for biomarkers that can assist in correct classification, including the distinctions between epithelial and non-epithelial NENs that have allowed reclassification of epithelial NETs in the spine, in the duodenum, and in the middle ear; the first two may be composite tumors with neuronal and glial elements, and as this feature is integral to the duodenal lesion, it is now classified as composite gangliocytoma/neuroma and neuroendocrine tumor (CoGNET). The many other aspects of differential diagnosis are detailed with recommendations for biomarkers that can distinguish NENs from non-neuroendocrine lesions that can mimic their morphology. The concepts of mixed neuroendocrine and non-neuroendocrine (MiNEN) and amphicrine tumors are clarified with information about how to approach such lesions in routine practice. Theranostic biomarkers that assist patient management are reviewed. Given the significant proportion of NENs that are associated with germline mutations that predispose to this disease, we explain the role of the pathologist in identifying precursor lesions and applying molecular immunohistochemistry to guide genetic testing.

Mixed neuroendocrine–nonneuroendocrine neoplasms of the gastrointestinal system: An update

Mixed neuroendocrine-nonneuroendocrine neoplasms (MiNENs) of the digestive tract are a rare heterogeneous group of tumors that present many challenges in terms of diagnosis and treatment. Over the years, the diagnostic criteria, classification, and clinical behavior of these tumors have been the subjects of ongoing debate, and the various changes in their nomenclature have strengthened the challenges associated with MiNENs. This review is performed to provide an understanding of the key factors involved in the evolution of the designation of these tumors as MiNEN, highlight the current diagnostic criteria, summarize the latest data on pathogenesis and provide information on available treatments. Moreover, this work seeks to increase the awareness about these rare neoplasms by presenting the clinicopathological features and prognostic factors that play important roles in their behavior and discussing their different regions of origin in the gastrointestinal system (GIS). Currently, the MiNEN category also includes tumors in the GIS with a nonneuroendocrine component and epithelial tumors other than adenocarcinoma, depending on the organ of origin. Diagnosis is based on the presence of both morphological components in more than 30% of the tumor. However, this value needs to be reconfirmed with further studies and may be a limiting factor in the diagnosis of MiNEN by biopsy. Furthermore, available clinicopathological data suggest that the inclusion of amphicrine tumors in the definition of MiNEN is not supportive and warrants further investigation. The diagnosis of these tumors is not solely based on immunohistochemical findings. They are not hybrid tumors and both components can act independently; thus, careful grading of each component separately is required. In addition to parameters such as the metastatic state of the tumor at the time of diagnosis and the feasibility of surgical resection, the aggressive potential of both components has paramount importance in the choice of treatment. Regardless of the organ of origin within the GIS, almost MiNENs are tumors with poor prognosis and are frequently encountered in the elderly and men. They are most frequently reported in the colorectum, where data from molecular studies indicate a monoclonal origin; however, further studies are required to provide additional support for this origin.

Focal neuroendocrine carcinoma mixed with adenocarcinoma of the gallbladder with aggressive lymph node metastasis in a patient who did not meet the mixed neuroendocrine-non-neuroendocrine neoplasm criteria

A 70-year-old Japanese woman who was treated for interstitial pneumonia (IP) with steroid therapy developed cholecystitis. A serial computed-tomography (CT) imaging showed irregular thickness of the fundus wall of the gallbladder and two rapidly enlarged lymph nodes (LNs): number (no.) 12 and no. 8a. Positron-emission tomography-computed tomography (PET-CT) scan showed an abnormal uptake at the site of the gallbladder tumor and those LNs. We subsequently performed open radical cholecystectomy and LN dissection of the no. 12 and 8a LNs, following complete remission of IP. The histology showed gallbladder adenocarcinoma, with a single focus of neuroendocrine carcinoma (NEC) component of less than 30%; Ki-67 index > 80%, synaptophysin (Syn) (+), chromogranin A (CgA) (+), and clusters of differentiation (CD) 56 (+) (T2bN1M0, Stage IIIB). LN no. 8a was diffusely metastatic with NEC components. LN no. 12c, which was adjacent to the cystic duct, revealed necrosis without apparent tumor cells, but was highly suspicious for tumor necrosis. The final diagnosis was adenocarcinoma of the gallbladder with focal NEC (< 30%), which did not meet the criteria for mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN). Postoperatively, she completed 4 cycles of adjuvant chemotherapy for NEC (Cisplatin plus Etoposide), and no recurrence was observed after 12 months.

Coexistence of superficial carcinogenesis of resident epithelium besides neuroendocrine neoplasm of the digestive tract

Background & Aims

Mixed neuroendocrine–non‐neuroendocrine neoplasm (MiNEN) is a rare neuroendocrine neoplasm (NEN) comprising dual neuroendocrine and non‐neuroendocrine components. Although the coexistence pattern of neuroendocrine and non‐neuroendocrine components in definitive MiNEN is thought to overlap, there may be a coexistent pattern of both components, such as superficial carcinoma adjacent to NEN. The present study evaluated the histopathological findings of the coexistence pattern of superficial carcinomas adjacent to NENs in the esophagogastrointestinal tract.

Methods

From 2000 to 2019, 35 serial NEN resections of the esophagus (n = 9), stomach (n = 3), and large intestine (n = 23), respectively, were performed at Gunma University Hospital. Borderline areas between NEN and resident superficial epithelium were observed in the 35 serial NEN cases as well as two additional cases from affiliated hospitals.

Results

Among the 35 serial NEN samples, squamous cell carcinomatous/dysplastic components were identified 77.8% (7/9 cases) of esophageal NENs, and adenocarcinomatous areas were seen in 66.7% (2/3 cases) of gastric NENs and 26% (6/23 cases) of colorectal NENs. Thus, all superficial carcinomatous components adjacent to NENs were observed as squamous cell carcinoma/dysplasia in esophagus and adenocarcinoma in stomach and large intestine, which showed histological characteristics as the resident epithelial pattern in each organ.

Conclusions

These findings suggested a potential “paratransformation” or “bystander effect” in resident epithelium by NENs. Thus, “bystander carcinogenesis” could be a pathogenic mechanism of resident epithelium transformation adjacent to NENs in the esophagogastrointestinal tract.

New Developments in Gastric Neuroendocrine Neoplasms

Purpose of Review

Gastric neuroendocrine neoplasms (g-NENs) are a rare type of stomach cancer. The three main subtypes have different pathogeneses, biological behaviours and clinical characteristics, so they require different management strategies. This article will provide an overview of g-NENs and highlight recent advances in the field.

Recent Findings

Molecular profiling has revealed differences between indolent and aggressive g-NENs, as well as a new somatic mutation responsible for some familial type I g-NENs. Novel biomarkers have been developed which will hopefully improve diagnosis, treatment, risk stratification and follow-up. Patient treatment is also changing, as evidence supports the use of less aggressive options (e.g. endoscopic surveillance or resection) in some patients with more indolent tumours.

Summary

g-NEN heterogeneity poses challenges in understanding and managing this rare disease. More basic science research is needed to investigate molecular pathogenesis, and future larger clinical studies will hopefully also further improve treatment and patient outcomes.

Gastric Mixed Adenoneuroendocrine Carcinoma with Revised Diagnosis after Retrospective Pathologic Review

Gastric mixed adenoneuroendocrine carcinoma (MANEC) is an entity defined by World Health Organization in 2010, which is composed of adenocarcinoma and neuroendocrine neoplasm. This is a very rare type of tumor in the stomach, which is estimated to be one to two per one million people per year on gastrointestinal track. In general, as MANEC often shows a poor prognosis, early diagnosis of the disease is important for achieving a favorable outcome. However, due to its rarity and histological heterogeneity, it is hard to suspect this disease initially, and sometimes this tumor is misdiagnosed as adenocarcinoma. The present case was a 76-year-old man who was initially diagnosed with gastric tubular adenocarcinoma without distant metastasis. Only 1 month after a curative surgery, multiple liver metastases were newly detected. Retrospective pathologic review resulted in a revised diagnosis as a gastric MANEC, and the patient underwent palliative systemic chemotherapy to achieve partial response.

Mixed neuroendocrine nonneuroendocrine neoplasms of the pancreas: a case report and literature review of pancreatic mixed neuroendocrine nonneuroendocrine neoplasm

A 36-year-old woman underwent left lateral hepatic lobectomy and tumor enucleation of the pancreatic head due to the diagnosis of mixed neuroendocrine nonneuroendocrine neoplasms (MiNENs). Her past medical history revealed an ill-defined mass in the pancreatic uncinate (approximately 1 cm in size) and liver nodules in segment II, suggesting a pancreatic neuroendocrine tumor (pNET) and liver metastases. After the operation, pathological examination showed that the lesion in the pancreas was MiNEN. The neuroendocrine component consisted of grade 1 (G1) NETs, and the nonneuroendocrine part was well-differentiated adenocarcinoma. Additionally, in hepatic lesions, the type of pancreaticobiliary duct in moderately differentiated adenocarcinoma indicated the source of tumor cells. We present the following case in accordance with the CARE reporting checklist. MiNENs of the pancreas are extremely rare and heterogeneous malignancies. Owing to the rarity of pancreatic MiNEN, no structured guidelines on preoperative diagnostics, therapy and follow-up exist thus far. Thus, problems in differential diagnosis and appropriate therapy may arise when treating suspected MiNEN patients. We performed a rigorous search on pancreatic MiNEN via PubMed and Web of Science. In total, 167 studies were identified, and 28 cases in 15 studies about pancreatic MiNEN were assessed. All the available information was listed and fully discussed.

Case report: composite pancreatic intraductal papillary mucinous neoplasm and neuroendocrine tumor: a new mixed neuroendocrine-non-neuroendocrine neoplasm?

BACKGROUND

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNEN) of the pancreas are extremely rare. Their pathogenesis and molecular landscape are largely unknown. Here, we report a case of mixed pancreatic intraductal papillary mucinous neoplasm (IPMN) and well-differentiated neuroendocrine tumor (NET) and identify its genetic alterations by next-generation sequencing (NGS).

CASE PRESENTATION

A fifty-year-old male was admitted into the hospital for evaluation of a pancreatic lesion detected during a routine examination. Abdominal ultrasound indicated a hypoechoic mass of 2.6 cm at the head of the pancreas. Malignancy was suspected and partial pancreatectomy was performed. Thorough histopathological examination revealed a mixed IPMN-NET. In some areas, the two components were relatively separated, whereas in other areas IPMN and NET grew in a composite pattern: The papillae were lined with epithelial cells of IPMN, and there were clusters of NET nests in the stroma of papillary axis. NGS revealed shared somatic mutations (KRAS, PCK1, MLL3) in both components. The patient has been uneventful 21 months after the surgery.

CONCLUSIONS

Our case provides evidence of a common origin for mixed IPMN-NET with composite growth features. Our result and literature review indicate that KRAS mutation might be a driver event underlying the occurrence of MiNEN. We also recommend the inclusion of mixed non-invasive exocrine neoplasms and neuroendocrine neoplasms into MiNEN.

Pancreatic Neuroendocrine Tumors: Molecular Mechanisms and Therapeutic Targets

Pancreatic neuroendocrine tumors (pNETs) are unique, slow-growing malignancies whose molecular pathogenesis is incompletely understood. With rising incidence of pNETs over the last four decades, larger and more comprehensive 'omic' analyses of patient tumors have led to a clearer picture of the pNET genomic landscape and transcriptional profiles for both primary and metastatic lesions. In pNET patients with advanced disease, those insights have guided the use of targeted therapies that inhibit activated mTOR and receptor tyrosine kinase (RTK) pathways or stimulate somatostatin receptor signaling. Such treatments have significantly benefited patients, but intrinsic or acquired drug resistance in the tumors remains a major problem that leaves few to no effective treatment options for advanced cases. This demands a better understanding of essential molecular and biological events underlying pNET growth, metastasis, and drug resistance. This review examines the known molecular alterations associated with pNET pathogenesis, identifying which changes may be drivers of the disease and, as such, relevant therapeutic targets. We also highlight areas that warrant further investigation at the biological level and discuss available model systems for pNET research. The paucity of pNET models has hampered research efforts over the years, although recently developed cell line, animal, patient-derived xenograft, and patient-derived organoid models have significantly expanded the available platforms for pNET investigations. Advancements in pNET research and understanding are expected to guide improved patient treatments.

Rectal mixed adenoneuroendocrine carcinoma: Case report

RATIONALE

Colorectal mixed neuroendocrine-nonneuroendocrine neoplasms constitute a rare group of gastrointestinal tumors composed by both neuroendocrine and nonneuroendocrine components. Nondiagnostic macroscopic features, specific histological features, and poor awareness of the disease are responsible for the underestimated incidence and conflicting data available. Due to lack of randomized clinical trials and validated clinical guidelines, diagnostic and therapeutic approach are based on the standard of care for pure colorectal neuroendocrine carcinomas or adenocarcinomas.

PATIENT CONCERNS

A 76-year-old caucasian male, without relevant medical or familial history, presented a positive faecal occult blood test during colorectal cancer screening.

DIAGNOSIS

Total colonoscopy identified a rectal lesion with biopsy showing a moderate rectal adenocarcinoma staged as cT2N0M0.

INTERVENTIONS

Anterior resection of the rectum with right ileostomy followed by local radiotherapy with radio-sensitising chemotherapy and adjuvant chemotherapy with capecitabine 1000 mg bid plus oxaliplatin 130 mg/m2. Due to chronic nodular pulmonary aspergillosis and chemotherapy induced immunosuppression patient was on 400 mg/daily of oral voriconazole.

OUTCOMES

Overall survival of 15 months after progression under first line treatment and under palliative chemotherapy with platinum plus etoposide regimen.

LESSONS

The reported case illustrates the challenge associated to the management of mixed neuroendocrine-nonneuroendocrine carcinomas due to lack of validated guidelines and scientific evidence. From diagnosis and staging to treatment, all steps must be tailored to individual clinical and histological features.

Anal canal mixed adenoneuroendocrine carcinoma in a young patient misdiagnosed as anal abscess

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) are rare tumours of gastrointestinal tract, extremely rare in anal canal. We report a case of misdiagnosed MiNEN in a 38-year-old woman initially conservatively treated for a supposed anal fistula. In a second proctological evaluation, biopsy of the anal neoformation was performed and the histological specimen diagnosed a MiNEN. The complete staging showed a disseminate disease and the patient started a chemotherapy schedule. After 6 months, stable disease was revealed at the last imaging performed and radical surgery was offered to the patient that is actually on oncological follow-up without recurrence at 1 year.

When Variants Collide: An Unusual Presentation of Metastatic Gastric Mixed Neuroendocrine-Non-Neuroendocrine Neoplasm

Gastrointestinal neuroendocrine neoplasms were recently reclassified into the 2019 World Health Organization schema into well-differentiated neuroendocrine tumors, poorly differentiated neuroendocrine carcinomas, and mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs). Among these, gastric MiNENs are exceedingly rare and often metastasize quickly without diagnostic clues. We present a refractory gastric MiNEN with unique presenting features. This case highlights the clinical spectrum of these tumors, the importance of accurate histochemical interpretation, and clinical management in the absence of formalized guidelines. Future therapies looking at novel targets and palliative symptom relief are needed.