Characterization of genome-wide copy number aberrations in colonic mixed adenoneuroendocrine carcinoma and neuroendocrine carcinoma reveals recurrent amplification of PTGER4 and MYC genes. Hum Pathol. 2018;73:16-25. [PMID: 28899736 DOI: 10.1016/j.humpath.2017.08.036]

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.

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.

Molecular Subtypes of Extra-pulmonary Neuroendocrine Carcinomas Identified by the Expression of Neuroendocrine Lineage-Specific Transcription Factors

Extra-pulmonary neuroendocrine carcinomas (EPNEC) represent a group of rare and heterogenous neoplasms with adverse clinical outcome. Their molecular profile is largely unexplored. Our aim was to investigate if the major transcriptional drivers recently described in high-grade pulmonary neuroendocrine carcinomas characterize distinct molecular and clinical subgroups of EPNEC. Gene expression of ASCL1, NEUROD1, DLL3, NOTCH1, INSM1, MYCL1, POU2F3, and YAP1 was investigated in a series of 54 EPNEC (including 10 cases with mixed components analyzed separately) and in a group of 48 pulmonary large cell neuroendocrine carcinomas (P-LCNEC). Unsupervised hierarchical cluster analysis classified the whole series into four major clusters. P-LCNEC were classified into two major clusters, the first ASCL1/DLL3/INSM1-high and the second (including four EPNEC) ASCL1/DLL3-low but INSM1-high. The remaining EPNEC cases were sub-classified into two other clusters. The first showed INSM1-high and alternative ASCL1/DLL3 or NEUROD1 high expression. The second was characterized mainly by MYCL1 and YAP1 overexpression. In the ten cases with mixed histology, ASCL1, DLL3, INSM1, and NEUROD1 genes were significantly upregulated in the neuroendocrine component. Higher gene-expression levels of NOTCH1 and INSM1 were associated with lower pT stage and negative nodal status. Low INSM1 gene expression was associated with shorter overall survival in the entire case series (p = 0.0017) and with a trend towards significance in EPNEC, only (p = 0.06). In conclusion, our results show that EPNEC possess distinct neuroendocrine-lineage-specific transcriptional profiles; moreover, low INSM1 gene expression represents a novel potential unfavorable prognostic marker in high-grade NECs including those in extra-pulmonary location.

Long-term survival of gastric mixed neuroendocrine-non-neuroendocrine neoplasm: Two case reports

BACKGROUND

Gastric mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN), which consists of neuroendocrine and non-neuroendocrine components, is quite rare. Until now, most data on gastric MiNEN come from clinical cases, without large-scale retrospective studies or controlled clinical trials. Consequently, no consensus regarding the origin, molecular characteristics, or appropriate treatment of MiNEN has been reached so far. We conducted chemotherapy of irinotecan plus cisplatin (IP regimen) and surgery in two patients with gastric MiNEN, which had never been used in treating this kind of tumor, leading to their long-term survival for more than 3 and 7 years, respectively.

CASE SUMMARY

We present two patients (one male and one female) with gastric MiNEN, with the primary manifestation of recurrent upper abdominal pain. After they were referred to our hospital, a diagnosis of gastric MiNEN was defined with the help of CT scan, and histopathological and immunohistochemical examinations on the samples of gastrointestinal endoscopy or radical surgery. The male patient (case 1) were found to have metastases in the reginal lymph nodes and the left liver. He received four cycles of IP regimens first, then the gastrectomy and partial left liver resection, followed by additional two cycles of IP chemotherapy. The female patient (case 2) underwent a laparoscopic gastrectomy, and received six cycles of IP regimen. She was found to have metastatic lesions in the right lung 2 years after that, and underwent video-assisted thoracoscopic surgery (VATS) of the lower lobe of the right lung. The two patients have now survived for more than 3 years and 7 years, respectively, without any evidence of recurrence or metastases.

CONCLUSION

IP regimen, combined with curative-intent surgery if feasible, could be considered as the priority in the choice of front-line chemotherapy for gastric MiNEN.

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.

Prostanoid Signaling in Cancers: Expression and Regulation Patterns of Enzymes and Receptors

Cancer-associated disturbance of prostanoid signaling provides an aberrant accumulation of prostanoids. This signaling consists of 19 target genes, encoding metabolic enzymes and G-protein-coupled receptors, and prostanoids (prostacyclin, thromboxane, and prostaglandins E2, F2α, D2, H2). The study addresses the systems biology analysis of target genes in 24 solid tumors using a data mining pipeline. We analyzed differential expression patterns of genes and proteins, promoter methylation status as well as tissue-specific master regulators and microRNAs. Tumor types were clustered into several groups according to gene expression patterns. Target genes were characterized as low mutated in tumors, with the exception of melanoma. We found at least six ubiquitin ligases and eight protein kinases that post-translationally modified the most connected proteins PTGES3 and PTGIS. Models of regulation of PTGIS and PTGIR gene expression in lung and uterine cancers were suggested. For the first time, we found associations between the patient’s overall survival rates with nine multigene transcriptomics signatures in eight tumors. Expression patterns of each of the six target genes have predictive value with respect to cytostatic therapy response. One of the consequences of the study is an assumption of prostanoid-dependent (or independent) tumor phenotypes. Thus, pharmacologic targeting the prostanoid signaling could be a probable additional anticancer strategy.

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.

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.

Antizyme Inhibitor 1 regulates matrikine expression and enhances the metastatic potential of aggressive primary prostate cancer

Molecular drivers of metastasis in patients with high-risk localized prostate cancer (PCa) are poorly understood. Therefore, we aim to study molecular drivers of metastatic progression in high-risk PCa patients. A retrospective matched case-control study of two clinico-pathologically identical groups of high-risk PCa patients was undertaken. One group developed metastatic recurrence (n=19) while the other did not (n=25). The primary index tumor was identified by a uro-pathologist, followed by DNA and RNA extraction for somatic copy number aberration (CNA) analysis and whole-transcriptome gene expression analysis. In vitro and in vivo studies included cell line manipulation and xenograft models. The integrative CNA and gene expression analyses identified an increase in AZIN1 gene expression within a focal amplification of 8q22.3, which was associated with metastatic recurrence of high-risk PCa patients in four independent cohorts. The effects of AZIN1 knockdown were evaluated, due to its therapeutic potential. AZIN1 knockdown effected proliferation and metastatic potential of PCa cells and xenograft models. RNA sequencing after AZIN1 knockdown in PCa cells revealed upregulation of genes coding for collagen subunits. The observed effect on cell migration after AZIN1 knockdown was mimicked when exposing PCa cells to bio-active molecules deriving from COL4A1 and COL4A2. Our integrated CNA and gene expression analysis of primary high-risk PCa identified the AZIN1 gene as a novel driver of metastatic progression, by altering collagen subunit expression. Future research should further investigate its therapeutic potential in preventing metastatic recurrence. Implications: AZIN1 was identified as driver of metastatic progression in high-risk PCa through matrikine regulation.

Mixed adenoneuroendocrine carcinoma (MANEC) of the lower gastrointestinal tract: A systematic review with Bayesian hierarchical survival analysis

BACKGROUND

Mixed adeno-neuroendocrine carcinomas (MANEC) are a subgroup of mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN) described as mixed neoplasms containing dual neuroendocrine and non-neuroendocrine components. The aim of this study was to appraise the prevalence of MANEC in the lower gastrointestinal (GI) tract and provide reliable estimates of survival.

METHOD

A systematic review was undertaken in accordance with PRISMA guidelines using PubMed, Embase, Cochrane Library of Systematic Review, Web of Science, and Scopus databases, and a Bayesian hierarchical survival pooled analysis was performed.

RESULTS

Of 182 unique records identified, 71 studies reporting on 752 patients met the inclusion criteria. Mean age was 64.2 ± 13.6, with a male-to-female ratio of 1.25. Overall, 60.3% of MANEC were located in the appendix, 29.3% in the colon, and 10.4% in the anorectum. More than a quarter (29%) of patients had stage IV disease at diagnosis, with higher prevalence in appendiceal than colonic and anorectal primaries. More than 80% had a high-grade (G3) endocrine component. Of the 152 patients followed up for a median of 20 months (interquartile range limits, 16.5-32), median overall survival was 12.3 months (95% credible interval [95%CrI], 11.3-13.7), with a 1.12 [95%CrI, 0.67-1.83] age-adjusted hazard ratio between metastatic and non-metastatic MANEC. Stage IV disease at diagnosis was more prognostically unfavorable in cases of colonic compared to anorectal origin.

CONCLUSION

MANEC is a clinically aggressive pathological entity. The results of this study provide new insights for the understanding of tumor location within the lower GI tract and its prognosis in terms of overall survival.

Chromosomal and molecular pathway alterations in the neuroendocrine carcinoma and adenocarcinoma components of gastric mixed neuroendocrine-nonneuroendocrine neoplasm

Gastric mixed adenoneuroendocrine carcinoma (MANEC) is a clinically aggressive subtype of mixed neuroendocrine-nonneuroendocrine neoplasm (MiNEN) with unclear clonal origin. In this study, we analyzed high-resolution copy number (CN) profiling data using the OncoScan CNV Assay in the neuroendocrine carcinoma (NEC) and adenocarcinoma components of eight MANECs. Some common CNVs, including the gain of CCNE1 (19q12) and the loss of FAT1 (4q35.2), were frequently detected in both components; these CNVs were verified by FISH, qPCR and immunohistochemistry staining assays in samples with sufficient material. The identification of common CNVs in both components supports the likelihood of single clonal origin of morphologically heterogeneous tumor cells and suggests several novel genetic events potentially involved in the development of gastric MANEC. We also detected and validated some CNVs and alterations specific for the NEC component, such as MAPK1 loss and MAPK signaling pathway alterations, which could contribute to the neuroendocrine differentiation of gastric MANEC. In addition, we found that the NEC component presented more CNVs and greater CN loss than the adenocarcinoma component (P = 0.007 and P = 0.004, respectively); the NEC components from different cases were not clustered in the hierarchical clustering analysis, indicating the marked genetic heterogenicity of the NEC component in gastric MANEC. In summary, this study describes the cytogenetic characteristics of each component of gastric MANEC, providing some clues for further studies on the development and progression of gastric MANEC as well as providing some potential therapeutic targets.

Case report: potential treatment of metastatic amphicrine carcinoma of the rectum with FOLFOXIRI chemotherapy

Amphicrine carcinoma (AmC) is a unique epithelial tumor displaying exocrine and endocrine features in the same cell. It shows an adenocarcinoma-like cellular form and has endocrine granules. There are few reports describing chemotherapy for AmC. Here, we describe a case with metastatic AmC from the rectum that was treated with FOLFOXIRI chemotherapy.

A 64-year-old man was diagnosed with a submucosal lesion on the scar produced after an endoscopic mucosal resection, which had been performed for adenocarcinoma of the rectum 2 years before. The endoscopic submucosal dissection revealed AmC. The abdominoperineal resection including lymph nodes dissection was performed. Thereafter, computed tomography showed multiple liver metastases, and FOLFOXIRI was administered. The best overall response was partial response, and progression-free survival was 8.7 months. After 16.0 months since first-line chemotherapy the patient died. We can therefore conclude that FOLFOXIRI may be effective for AmC of the rectum.

Mixed epithelial endocrine neoplasms of the colon and rectum - An evolution over time: A systematic review

BACKGROUND

Mixed tumors of the colon and rectum, composed of a combination of epithelial and endocrine elements of benign and malignant potential are rare neoplasms. These can occur anywhere in the gastrointestinal tract and are often diagnosed incidentally. Though they have been a well-documented entity in the pancreas, where the exocrine-endocrine mixed tumors have been known for a while, recognition and accurate diagnosis of these tumors in the colon and rectum, to date, remains a challenge. This is further compounded by the different terminologies that have been attributed to these lesions over the years adding to increased confusion and misclassification. Therefore, dedicated literature reviews of these lesions in the colon and rectum are inconsistent and are predominantly limited to case reports and case series of limited case numbers. Though, most of these tumors are high grade and of advanced stage, intermediate and low grade lesions of these mixed tumors are also increasingly been reported. There are no established independent consensus based guidelines for the therapeutic patient management of these unique lesions.

AIM

To provide a comprehensive targeted literature review of these complex mixed tumors in the colon and rectum that chronicles the evolution over time with summarization of historical perspectives of terminology and to further our understanding regarding their pathogenesis including genomic landscape, clinicoradiological features, pathology, treatment, prognosis, the current status of the management of the primary lesions, their recurrences and metastases.

METHODS

A comprehensive review of the published English literature was conducted using the search engines PubMed, MEDLINE and GOOGLE scholar. The following search terms ["mixed tumors colon" OR mixed endocrine/neuroendocrine tumor/neoplasm/lesion colon OR adenocarcinoma and endocrine/neuroendocrine tumor colon OR mixed adenocarcinoma and endocrine/neuroendocrine carcinoma colon OR Amphicrine tumors OR Collision tumors] were used. Eligibility criteria were defined and all potential relevant items, including full articles and/or abstracts were independently reviewed, assessed and agreed upon items were selected for in-depth analysis.

RESULTS

In total 237 full articles/abstracts documents were considered for eligibility of which 45 articles were illegible resulting in a total of 192 articles that were assessed for eligibility of which 139 have been selected for reference in this current review. This seminal manuscript is a one stop article that provides a detailed outlook on the evolution over time with summarization of historical perspectives, nomenclature, clinicoradiological features, pathology, treatment, prognosis and the current status of the management of both the primary lesions, their recurrences and metastases. Gaps in knowledge have also been identified and discussed. An important outcome of this manuscript is the justified proposal for a new, simple, clinically relevant, non-ambiguous terminology for these lesions to be referred to as mixed epithelial endocrine neoplasms (MEENs).

CONCLUSION

MEEN of the colon and rectum are poorly understood rare entities that encompass an extensive range of heterogeneous tumors with a wide variety of combinations leading to tumors of high, intermediate or low grade malignant potential. This proposed new revised terminology of MEEN will solve the biggest hurdle of confusion and misclassification that plagues these rare unique colorectal neoplasms thus facilitating the future design of multi institutional prospective randomized controlled clinical trials to develop and evaluate newer therapeutic strategies that are recommended for continued improved understanding and personal optimization of clinical management of these unique colorectal neoplasms.

Looking into digestive mixed neuroendocrine - nonneuroendocrine neoplasms: subtypes, prognosis, and predictive factors

Mixed neuroendocrine - nonneuroendocrine neoplasms (MiNENs) of the digestive system represent a challenge for both pathologists and clinicians. Their nomenclature has changed several times, and their diagnostic criteria, classification and clinical behaviour have been matter of debate over the years. Although several attempts have been made to elucidate the pathogenesis and biology of MiNENs, some issues remain open. This review will provide: a historical background that helps in understanding the evolution of the concept and nomenclature of mixed neoplasms; a revision of the knowledge on this topic, including molecular aspects, to give the reader a comprehensive and practical overview on this challenging field of pathology; a focus on the diagnostic criteria and on the determination of prognostic and predictive factors; and a description of the different tumour types in the different sites of origin.

Clinical implications of mismatch repair deficiency screening in patients with mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN)

INTRODUCTION

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN) are rare tumors, mainly encountered in the gastroenteropancreatic tract. Based on the limited available data, MiNEN is usually a highly aggressive neoplasm combining a high-grade neuroendocrine and a non-neuroendocrine component, associated with a poor prognostic outlook. Deficient DNA mismatch repair (MMR) results in microsatellite instability, which is a useful screening marker for identifying patients with Lynch syndrome and a prognostic factor for chemotherapeutic interventions. Little information on MMR status in MiNEN is available in published studies. Therefore, the purpose of this study was to explore the status and putative role of MMR on MiNEN.

METHODS

We investigated the MMR status in 44 cases and characterized their clinicopathological features and prognoses. Immunohistochemistry was performed for four mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2).

RESULTS

Mean age at diagnosis was 61 years, and 75% of the patients were male. Lymph node metastases were observed in 14 (35.9%) patients. The most common tumor localizations were gastric (28 patients, 63.6%). Lack of immunohistochemical expression of MMR proteins was shown in 38.6% of cases. The common deletion rates of one or more proteins were 29.4% (5/17) for MLH1/PMS2 and 23.5% (4/17) for MLH1. Correlation between clinicopathological parameters showed that MMR deficiency was significantly associated with early TNM stage and better prognoses in patients with MiNEN.

CONCLUSION

MiNENs showed frequent losses of MMR protein expression, which contributes to the knowledge of the pathological and clinical aspects of MiNEN tumors.

Survival Profile and Prognostic Factors for Appendiceal Mixed Neuroendocrine Non-neuroendocrine Neoplasms: A SEER Population-Based Study

Introduction

Mixed neuroendocrine non-neuroendocrine neoplasm (MiNEN) is a rare form of neuroendocrine neoplasms (NENs). The purpose of this study was to investigate the characteristics and survival profile of appendiceal MiNENs, with a view of providing robust clinical features of this rare disease.

Methods

Patients were selected from the Surveillance, Epidemiology, and End Results database (2004–2016). The prognosis of MiNEN (n = 315) was compared with other histological subtypes including neuroendocrine tumor (NETs) (n = 1734), neuroendocrine carcinoma (NECs) (n = 375), goblet cell carcinoid (GCC) (n = 968), signet ring cell carcinoma (n = 463), mucinous adenocarcinoma (MAC) (n = 2355), and non-mucinous adenocarcinoma (NMAC) (n = 1187) in the appendix. Age-adjusted incidence was calculated using Joinpoint regression. The Cox proportional hazards model and the Fine–Gray competing risk model were used to perform overall survival (OS) and cancer-specific mortality (CSM) analyses, respectively.

Results

The age-adjusted incidence of MiNENs increased from 0.01/100,000 person-years in 2004 to 0.07/100,000 person-years in 2016. The 3-, 5-, and 10-year OS rates for MiNENs were 69.5, 57.4, and 43.7%, respectively, and the corresponding CSM rates were 23.1, 36.4, and 45.1%, respectively. Multivariate analysis revealed that the prognosis of MiNENs was worse than that of NETs, NECs, GCC, and MAC but better than that of NMAC and signet ring cell carcinoma. Tumor extension was the only independent factor influencing the prognosis of MiNENs, but tumor size, grade, and surgical approaches were not. Moreover, when compared with local excision or appendectomy, extensive surgery such as hemicolectomy or colectomy did not prolong the survival of individuals with MiNENs.

Conclusion

MiNEN is a rare but aggressive tumor with a poor prognosis differing from NENs, GCC and adenocarcinomas. To improve the prognosis of the disease, early diagnosis and comprehensive evaluation are necessary.

Mixed adenoneuroendocrine carcinoma of the gallbladder, amphicrine type: Case report and review of literature

Amphicrine type mixed adenoneuroendocrine carcinoma (MANEC), also known as amphicrine carcinoma, is an exceedingly rare neoplasm comprising of tumor cells simultaneously demonstrating both neuroendocrine and exocrine differentiation. Majority of reported cases were found in tubular gastrointestinal tracts such as colon. Herein, we report the first case of amphicrine carcinoma in gallbladder in a 57-year-old female who presented with abdominal pain, vomiting, and gallbladder mass on imaging followed by radical cholecystectomy. Macroscopically, the tumor was a polypoid solid mass with a firm and tan-white cut surface located at the gallbladder fundus. Histologically, the tumor cells were composed of monotonous-appearing signet-ring cells with fine chromatin, variably conspicuous nucleoli, brisk mitotic figures, and spotty necrosis. They were loosely clustered, forming nests and cords but no glandular formation. Immunohistochemically, the entire tumor showed strong and diffuse immunoreactivity for CDX2, p53, and synaptophysin, with patchy positivity for CD56, chromogranin, and INSM1. Kreyberg stain highlighted both intracytoplasmic and extracellular mucin. Ki-67 proliferation index was approximately 70%. Next-generation sequencing performed on a 724 cancer-related gene panel identified TP53 mutation at c.844C>T (p.R282W). To our knowledge, this is the first case of amphicrine carcinoma in gallbladder. It highlights the complex dynamism and controversial pathogenesis of this unique entity, the exact mechanism and clinicopathologic behavior of which are not yet understood.

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

Mixed neuroendocrine non-neuroendocrine neoplasms (MiNENs) represent a rare diagnosis of the gastro-entero-pancreatic tract. Evidence from the current literature regarding their epidemiology, biology, and management is of variable quality and conflicting. Based on available data, the MiNEN has an aggressive biological behaviour, mostly driven by its (often high-grade) neuroendocrine component, and a dismal prognosis. In most cases, the non-neuroendocrine component is of adenocarcinoma histology. Due to limitations in diagnostic methods and poor awareness within the scientific community, the incidence of MiNENs may be underestimated. In the absence of data from clinical trials, MiNENs are commonly treated according to the standard of care for pure neuroendocrine carcinomas or adenocarcinomas from the same sites of origin, based on the assumption of a biological similarity to their pure counterparts. However, little is known about the molecular aberrations of MiNENs, and their pathogenesis remains controversial; molecular/genetic studies conducted so far point towards a common monoclonal origin of the two components. In addition, mutations in tumour-associated genes, including TP53, BRAF, and KRAS, and microsatellite instability have emerged as potential drivers of MiNENs. This systematic review (91 full manuscripts or abstracts in English language) summarises the current reported literature on clinical, pathological, survival, and molecular/genetic data on MiNENs.