Skip to content

This website uses cookies

This website uses cookies to improve user experience. By using our website you consent to all cookies in accordance with our Cookie Policy.

Learn more

Neuroendocrine Tumors

Neuroendocrine tumors represent a heterogenous group arising from a specialized cell population in the neuroendocrine system.

Neuroendocrine System

The neuroendocrine system is composed of specialized cells, which combine the properties of neuronal cells that respond to neural stimuli as well as endocrine cells that synthesize and excrete hormones, amines or peptides into the bloodstream (Asa, Rosa, and Mete. 2020). In addition, these cells express specific protein markers such as synaptophysin in the membranes of intra-cytoplasmic small presynaptic-like vesicles or chromogranin A in large dense core hormone granules (Klöppel G. 2017) (Figure 1).

Cells expressing neuronal and endocrine properties with specific markers.
Figure 1: Morphological similarities between the neuroendocrine cells with the nerve and endocrine cells regarding secretory granules and small vesicles (Adapted from Waldum et al. 2018).

Neuroendocrine cells are distributed throughout the body, including:

  • glands such as the pituitary, parathyroids and adrenals

  • clusters within glands, such as islet cells in the pancreas secreting insulin and C cells in the thyroid secreting calcitonin

  • scattered within the exocrine parenchyma, particularly in the gastrointestinal (GI) and respiratory tracts (Oronsky B et al. 2017)


  • Asa, Sylvia L., Stefano La Rosa, and Ozgur Mete. 2020. The Spectrum of Neuroendocrine Neoplasia: A Practical Approach to Diagnosis, Classification and Therapy. Springer Nature. DOI:

  • Klöppel, Günter. 2017. “Neuroendocrine Neoplasms: Dichotomy, Origin and Classifications.” Visceral Medicine 33(5): 324–30. DOI: 10.1159/000481390

  • Waldum, Helge L. et al. 2018. “Not Only Stem Cells, but Also Mature Cells, Particularly Neuroendocrine Cells, May Develop into Tumours: Time for a Paradigm Shift.” Therapeutic Advances in Gastroenterology 11: 1756284818775054. DOI: 10.1177/1756284818775054

  • Oronsky, Bryan, Patrick C. Ma, Daniel Morgensztern, and Corey A. Carter. 2017. “Nothing But NET: A Review of Neuroendocrine Tumors and Carcinomas.” Neoplasia 19(12): 991–1002. DOI: 10.1016/j.neo.2017.09.002