Editorial
Copyright ©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Oncol. Nov 15, 2024; 16(11): 4326-4332
Published online Nov 15, 2024. doi: 10.4251/wjgo.v16.i11.4326
Practical hints for the diagnosis of mixed neuroendocrine-non-neuroendocrine neoplasms of the digestive system
Paola Mattiolo
Paola Mattiolo, Department of Diagnostics and Public Health, Section of Pathology, University of Verona, University and Hospital Trust of Verona, Verona 37134, Italy
Paola Mattiolo, Department of Pathology, Heinrich Heine University and University Hospital of Duesseldorf, Duesseldorf 40225, Germany
Author contributions: Mattiolo P contributed to this paper, designed the overall concept and outline of the manuscript, provided the discussion and design of the manuscript, and wrote the manuscript.
Conflict-of-interest statement: The authors declare that they have no conflict of interest.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Paola Mattiolo, MD, Research Fellow, Department of Diagnostics and Public Health, Section of Pathology, University of Verona, University and Hospital Trust of Verona, Piazzale L.A. Scuro 10, Verona 37134, Italy. [email protected]
Received: March 26, 2024
Revised: June 6, 2024
Accepted: July 15, 2024
Published online: November 15, 2024
Processing time: 212 Days and 15.4 Hours
Abstract

In this editorial, a comment on the article by Díaz-López et al published in the recent issue of the 2024 is provided. We focus on the practical implications critical for providing a correct and complete diagnosis of mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) in the gastrointestinal system. The diagnosis of MiNEN begins with the recognition of neuroendocrine features in one component of a biphasic tumor. The non-neuroendocrine counterpart can be virtually represented by any neoplastic type, even though the most frequent histologies are glandular and squamous. However, qualification of the neuroendocrine component requires histological and immunohistochemical confirmation. Neuroendocrine tumors are characterized by a peculiar architectural organization and bland nuclei with granular “salt and pepper” chromatin. Although neuroendocrine carcinomas have multiple and variable presentations, they typically show a solid or organoid architecture. The histological aspect needs to be confirmed by immunohistochemistry, and a diagnosis is confirmed whenever the expression of keratin and neuroendocrine markers is observed. Once both histopathological and immunohistochemical features of neuroendocrine neoplasms are identified, it is important to consider the three major pitfalls of MiNEN diagnostics: (1) Entrapment of neuroendocrine non-neoplastic cells within the tumor mass; (2) Differential diagnosis with amphicrine neoplasms; and (3) Differential diagnosis of tumors that partially express neuroendocrine markers. According to the current guidelines for diagnosing digestive MiNEN, each component must represent at least 30% of the entire neoplastic mass. Although the high-grade histopathological subtype frequently determines disease prognosis, both components can significantly affect prognosis. Thus, if one of the components, either neuroendocrine or non-neuroendocrine, does not fulfill the volumetric criteria, the guidelines still encourage reporting it. These strict criteria are essential for correctly recognizing and characterizing digestive MiNENs. This task is essential because it has prognostic relevance and substantial potential value for guiding further studies in this field. In the future, systematic analyses should be performed to validate or reconsider the current 30% cutoff value.

Keywords: Mixed neuroendocrine-non-neuroendocrine neoplasm; Digestive system; Neuroendocrine neoplasm; Immunohistochemistry

Core Tip: Mixed neuroendocrine-non-neuroendocrine neoplasms are a heterogeneous group of neoplastic diseases that share histological and immunohistochemical features. The most important factor is the uncertain presence of a neuroendocrine component. The presence of entrapped neuroendocrine cells, differential diagnosis of amphicrine neoplasms, and neuroendocrine expression in non-neuroendocrine carcinoma can lead to misdiagnosis. Current guidelines require the fulfillment of volumetric criteria, but the prognostic relevance of the current cutoff remains to be proven.