Neuroendocrine neoplasms of the appendix, colon and rectum

Marco Volante, Federica Grillo, Federica Massa, Francesca Maletta, Luca Mastracci, Michela Campora, Jacopo Ferro, Alessandro Vanoli, Mauro Papotti

Research output: Contribution to journalReview articlepeer-review


Neuroendocrine neoplasms of the appendix, colon and rectum are classified according to the most recent WHO classification as neuroendocrine tumors (NET), neuroendocrine carcinomas (NEC) and mixed neuroendocrine-non neuroendocrine neoplasms (MiNENs). NECs and MiNENs are aggressive neoplasms requiring multimodal treatment strategies. By contrast, NETs are, in most cases, indolent lesions occurring as incidental findings in the appendix or as polyps in the rectum. While most appendiceal and rectal NETs are considered relatively non-aggressive neoplasms, a few cases, may show a more aggressive clinical course. Unfortunately, clinical/pathological characteristics to select patients at high risk of recurrence/metastases are poorly consolidated. Diagnosis is generally easy and supported by the combination of morphology and immunohistochemistry. Differential diagnostic problems are for NECs/MiNENs with poorly differentiated adenocarcinomas, when immunohistochemical neuroendocrine markers are not obviously positive, whereas for NETs they are represented by the rare appendiceal tubular and clear cell variants (which may be confused with non-neuroendocrine cancers) and rectal L-cell tumors which may be chromogranin negative and prostatic marker positive.

Original languageEnglish
Pages (from-to)19-27
Number of pages9
Issue number1
Publication statusPublished - Feb 1 2021


  • appendix
  • colon
  • neuroendocrine
  • rectum
  • tumor

ASJC Scopus subject areas

  • Pathology and Forensic Medicine


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