Classification of neuroendocrine neoplasms: lights and shadows

Rev Endocr Metab Disord. 2021 Sep;22(3):527-538. doi: 10.1007/s11154-020-09612-2. Epub 2020 Nov 9.


Neuroendocrine neoplasms (NENs) are a heterogeneous group of neoplastic proliferations showing different morphological features, immunophenotype, molecular background, clinical presentation, and outcome. They can virtually originate in every organ of the human body and their classification is not uniform among different sites. Indeed, as they have historically been classified according to the organ in which they primarily arise, the different nomenclature that has resulted have created some confusion among pathologists and clinicians. Although a uniform terminology to classify neuroendocrine neoplasms arising in different systems has recently been proposed by WHO/IARC, some issues remain unsolved or need to be clarified. In this review, we discuss the lights and shadows of the current WHO classifications used to define and characterize NENs of the pituitary gland, lung, breast and those of the head and neck region, and digestive and urogenital systems.

Keywords: Classification; Neuroendocrine carcinoma; Neuroendocrine neoplasm; Neuroendocrine tumor.

Publication types

  • Review

MeSH terms

  • Humans
  • Neuroendocrine Tumors* / diagnosis