Colorectal Neoplasm with Predominant Neuroendocrine Immunophenotype: Where does Adenocarcinoma End?
Clinical Practice
Gabrielė Cibulskaitė
Vilnius University, Lithuania
Rokas Stulpinas
Vilnius University, Lithuania
Eligijus Poškus
Vilnius University, Lithuania
Skaistė Tulytė
Vilnius University, Lithuania
Ugnius Mickys
Vilnius University, Lithuania
Published 2022-04-27
https://doi.org/10.15388/LietChirur.2022.21.58
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Keywords

mixed neuroendocrine non-neuroendocrine neoplasm
MiNEN
mixed adeno-neuroendocrine carcinoma MANEC
large cell neuroendocrine carcinoma
colorectal neoplasm

How to Cite

1.
Cibulskaitė G, Stulpinas R, Poškus E, Tulytė S, Mickys U. Colorectal Neoplasm with Predominant Neuroendocrine Immunophenotype: Where does Adenocarcinoma End?. LS [Internet]. 2022Apr.27 [cited 2022Aug.10];21(1):56-4. Available from: https://www.journals.vu.lt/lietuvos-chirurgija/article/view/27421

Abstract

MiNEN (mixed neuroendocrine-non-neuroendocrine neoplasm) is described in the 5th edition WHO classification of tumors of the digestive system as a mixed neoplasm, composed of neuroendocrine and non-neuroendocrine parts, each accounting for at least 30% of the tumor. Recently this formal criterion has been criticized based on the theory that both of these components could have a monoclonal origin and non-neuroendocrine cells develop neuroendocrinicity in the later evolutionary steps of adenocarcinoma. For this reason, the identification of pure adenocarcinoma component, that was overgrown by a more aggressive clone with neuroendocrine features, in a pathological specimen can be difficult and, in some cases, even impossible. So, it is likely that at least some of large cell neuroendocrine carcinomas follow the same pathway, a theory that is further supported by adenocarcinoma-like molecular alterations in these tumors. Precise diagnosis (which means identifying and naming each tumor component regardless of its size) is essential for a personalized treatment strategy. We present an illustrative case of a rectal neoplasm that could be classified as a poorly differentiated neuroendocrine carcinoma, but exhibits morphological heterogeneity, mucin production and has a typical KRAS mutation pointing to adenocarcinomatous origin, which makes MiNEN a more accurate diagnosis. The article discusses the key points in classification, pathogenesis, and diagnostic approach to help effectively manage such neoplasms.

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