Genetic alterations in gastric amphicrine carcinomas and comparison with gastric mixed neuroendocrine-non-neuroendocrine neoplasms

Gastric Carcinoma in Autoimmune Gastritis: A Histopathologic and Molecular Study

Patients with autoimmune gastritis (AIG) have a 13-fold risk of developing type-1 neuroendocrine tumors, whereas the risk for gastric adenocarcinoma is still uncertain. Here we describe the clinicopathologic and molecular features of a series of gastric carcinomas (GC) arising in the context of AIG. A total of 26 AIG-associated GC specimens were collected from 4 Italian Institutions. Immunohistochemistry for MUC1, MUC2, MUC5AC, MUC6, CDX2, HER2, PD-L1, CLDN18, mismatch repair (MMR) proteins, and p53 and EBV-encoded RNA (EBER) in situ hybridization were performed. Histologic and immunohistochemical features were jointly reviewed by 5 expert gastrointestinal pathologists. Next-generation sequencing analysis (TrueSight Oncology 500, Illumina) of 523 cancer-related genes was performed on 19 cases. Most tumors were diagnosed as pT1 (52%) and they were located in the corpus/fundus (58%) and associated with operative link for gastritis assessment stage II gastritis (80.8%), absence of parietal cells, complete intestinal metaplasia, and enterochromaffin-like-cell micronodular hyperplasia. Only 4 (15.4%) GCs were diagnosed during follow-up for AIG. The following histotypes were identified: 20 (77%) adenocarcinomas; 3 (11%) mixed neuroendocrine-non-neuroendocrine neoplasms, and 2 (8%) high-grade solid adenocarcinomas with focal neuroendocrine component, 1 (4%) adenocarcinoma with an amphicrine component. Overall, 7 cases (27%) showed MMR deficiency, 3 (12%) were positive (score 3+) for HER2, 6 (23%) were CLDN18 positive, and 11 (42%) had PD-L1 combined positive score ≥ 10. EBER was negative in all cases. Molecular analysis revealed 5/19 (26%) microsatellite instability (MSI) cases and 7 (37%) tumor mutational burden (TMB) high. The most frequently altered genes were TP53 (8/19, 42%), RNF43 (7/19, 37%), ERBB2 (7/19, 37% [2 amplified and 5 mutated cases]), ARID1A (6/19, 32%), and PIK3CA (4/19, 21%). In summary, AIG-associated GCs are often diagnosed at low stage in patients with longstanding misrecognized severe AIG; they often display a neuroendocrine component or differentiation, have relatively higher rates of MMR deficiency, and TMB high.

Double Digest: A Rare Case Report of Amphicrine Gastric Carcinoma Co-occurring With Papillary Thyroid Carcinoma

With improved cancer treatments and patient lifespans, the incidence of a second cancer diagnosis in a person's lifetime is increasing. While dual cancer diagnoses during one's lifetime are becoming more common, diagnosis with two separate cancers simultaneously is less so. In this report we present a 55-year-old obese woman with a history of chronic lymphocytic thyroiditis and a non-specific family history of thyroid cancer who received synchronous diagnoses of amphicrine carcinoma (AC) and papillary thyroid carcinoma (PTC) during work-up for bariatric surgery. AC is a very rare form of gastric cancer characterized by the presence of both endocrine and epithelial cell components within the same cell with only a few case reports in the literature. This is the first case report to present the co-occurrence of AC with PTC.

Comprehensive Multiomics Analyses Establish the Optimal Prognostic Model for Resectable Gastric Cancer : Prognosis Prediction for Resectable GC

BACKGROUND

Prognostic models based on multiomics data may provide better predictive capability than those established at the single-omics level. Here we aimed to establish a prognostic model for resectable gastric cancer (GC) with multiomics information involving mutational, copy number, transcriptional, methylation, and clinicopathological alterations.

PATIENTS AND METHODS

The mutational, copy number, transcriptional, methylation data of 268, 265, 226, and 252 patients with stages I-III GC were downloaded from the TCGA database, respectively. Alterations from all omics were characterized, and prognostic models were established at the individual omics level and optimized at the multiomics level. All models were validated with a cohort of 99 patients with stages I-III GC.

RESULTS

TTN, TP53, and MUC16 were among the genes with the highest mutational frequency, while UBR5, ZFHX4, PREX2, and ARID1A exhibited the most prominent copy number variations (CNVs). Upregulated COL10A1, CST1, and HOXC10 and downregulated GAST represented the biggest transcriptional alterations. Aberrant methylation of some well-known genes was revealed, including CLDN18, NDRG4, and SDC2. Many alterations were found to predict the patient prognosis by univariate analysis, while four mutant genes, two CNVs, five transcriptionally altered genes, and seven aberrantly methylated genes were identified as independent risk factors in multivariate analysis. Prognostic models at the single-omics level were established with these alterations, and optimized combination of selected alterations with clinicopathological factors was used to establish a final multiomics model. All single-omics models and the final multiomics model were validated by an independent cohort. The optimal area under the curve (AUC) was 0.73, 0.71, 0.71, and 0.85 for mutational, CNV, transcriptional, and methylation models, respectively. The final multiomics model significantly increased the AUC to 0.92 (P < 0.05).

CONCLUSIONS

Multiomics model exhibited significantly better capability in predicting the prognosis of resectable GC than single-omics models.

Clinicopathological and genetic characteristics of gastric neuroendocrine tumour (NET) G3 and comparisons with neuroendocrine carcinoma and NET G2

AIMS

To characterise the clinicopathological and genetic characteristics of gastric neuroendocrine tumour G3 (gNET G3) and to compare them with those of gastric neuroendocrine carcinoma (gNEC) and gNET G2.

METHODS AND RESULTS

A total of 115 gastric neuroendocrine neoplasms (NENs) were included, of which gNET G3 was different from gNET G1/G2 in terms of tumour location (P = 0.029), number (P = 0.003), size (P = 0.010), the Ki67 index (P < 0.001), lymph node metastasis (P < 0.001) and TNM stage (P = 0.011), and different from gNEC/gastric mixed neuroendocrine-non-neuroendocrine neoplasm (gMiNEN) in terms of tumour size (P = 0.010) and the Ki67 index (P = 0.001). High-resolution copy number (CN) profiling and validation experiments showed CN gains and high expression of DLL3 in gNET G3. Hierarchical clustering analysis based on CN characteristics showed that gNET G3 was separated from gNEC but mixed with gNET G2. In gene set enrichment analysis, eight pathways were significantly enriched in gNEC when comparing gNET G3 and gNEC (P < 0.05), while no pathways were enriched when comparing gNET G3 and gNET G2. Whole-exome sequencing and validation experiments showed nonsense mutation of TP53 in one gNET G3, with wild-type staining for p53. In gNEC, TP53 mutations were detected in four of eight cases, and abnormal expression of p53 was detected in all cases.

CONCLUSION

Gastric NET G3 is a distinct entity with unique genetic characteristics, which are different from those of gNEC than gNET G2. Our results provide insight into some molecular alterations that may contribute to the development and progression of gNET G3 and serve as potential therapeutic targets.

Gastric Amphicrine Carcinoma Showing Neuroendocrine and Pancreatic Acinar Cell Differentiation. Lesson from a Challenging Case Opening New Perspectives in the Diagnostic Work-Up of Gastric Neuroendocrine Neoplasms

Amphicrine carcinomas are epithelial neoplasms composed of cells with co-existing exocrine-neuroendocrine phenotype and are challenging lesions from both diagnostic and therapeutic perspectives.Here, we report the case of a 63-year-old male patient with a gastric nodule that was endoscopically biopsied, revealing histological features of a type 3 well-differentiated gastric neuroendocrine tumor (NET). At imaging, the lesion was single and limited to the stomach, but did not present In-111Octreotide uptake, despite SSTR2A immunohistochemical expression. The patient underwent a wedge resection of the gastric wall, with a final pathological diagnosis of amphicrine carcinoma with pancreatic acinar cell and neuroendocrine features (pT1b). Predictive immunohistochemistry showed microsatellite stability and negative HER2 status. Hotspot targeted deep sequencing of 57 genes showed no somatic mutation, in agreement with the low mutational burden reported for gastric amphicrine carcinomas. Due to a low stage of the tumor and the poor performance status of the patient, no additional oncological treatment was administered. The patient was disease-free after 18 months.This unusual case highlights the importance of considering amphicrine carcinoma in the diagnostic work-up of gastric type 3 NET. This can be done by including in the immunohistochemical panel non-neuroendocrine markers, such as the pancreatic acinar cell and glandular ones. Correct pathological diagnosis is pivotal to determine the appropriate staging (NET vs exocrine one) for surgical and oncological management.

Recurrent gastric amphicrine tumor with neuroendocrine and pancreatic acinar cell differentiation and somatic MEN1 inactivation arisen during immunotherapy

Amphicrine neoplasms (ANs) are poorly understood epithelial malignancies composed of cells with co-existing exocrine-neuroendocrine features. Here, we report a recurrent mucin-producing gastric amphicrine tumor co-expressing neuroendocrine (chromogranin-A, synaptophysin, and CD56) and pancreatic acinar cell (BCL10 and trypsin) markers, arisen in a 64-year-old woman during adjuvant immunotherapy for melanoma. Ki-67 was < 2%. The gastric background context was atrophic gastritis. Next-generation sequencing showed MEN1 mutation (p.P71fs*42) coupled with loss of heterozygosity. The key lessons were as follows: (1) gastric ANs can show the co-existence of exocrine mucin-producing elements with neuroendocrine and pancreatic acinar differentiation; (2) they may represent a new entity arising in the context of atrophic gastritis and during immunotherapy; (3) they should be considered in the diagnostic workup of gastric neuroendocrine tumors; and (4) their molecular profile can show striking similarities with well-differentiated neuroendocrine tumors. These findings may be of help to improve the knowledge and the biological taxonomy of ANs.

Updates in histopathological classification and tissue biomarkers of digestive neuroendocrine neoplasms: What the clinician should know

Histopathological classifications of neuroendocrine neoplasms (NEN) change regularly and the latest WHO classification published in 2022, which concerns all NEN in the body, attempts to standardize classifications in the different locations. Differentiation and proliferation mainly assessed by Ki-67 index are still the cornerstone of those classifications. However, many markers are now used for diagnostic (to check neuroendocrine differentiation, to identify the site of origin of a metastasis, to help separating high-grade neuroendocrine tumors/NET and neuroendocrine carcinoma/NEC), prognostic or theranostic purposes. NENs are often heterogeneous and this can lead to difficulties in classifications, biomarker and prognostic assessment. These different points are discussed successively in this review, insisting especially on the frequent digestive, gastro-entero-pancreatic (GEP) localizations.

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.