About the condition

Neuroendocrine tumours (NETs) are neoplasms that arise from cells of the endocrine (hormonal) and nervous systems and can arise at many sites in the body.

Types of Neuroendocrine tumours (NETs)

  • Gastrointestinal - Gastric, duodenal, pancreatic, small intestine, appendiceal, colon, rectum, ovary, unknown primary.
  • Thorax – lung
  • Neck/Thorax - Thyroid, parathyroid, thymus
  • Pancreas – Non-functioning. Functioning (gastrinoma, Vasoactive Intestinal Peptide [VIP]-oma, insulinoma, somatostatinoma glucagonoma).
  • Multiple endocrine neoplasia (MEN) -
  • MEN1 - Parathyroid, anterior pituitary, enteropancreatic endocrine cells.
  • MEN2A - Medullary thyroid, phaeochromocytoma, primary parathyroid hyperplasia.
  • MEN2B - Medullary thyroid, phaeochromocytoma, mucosal neuromas, intestinal ganglioneuromas and marfanoid habitus and other skeletal abnormalities.
  • Adrenal - Phaeochromocytoma.
  • Extra-adrenal - Paraganglioma.
  • Goblet cell – Appendix
  • Other - Merkel cell skin cancer, pituitary neuroendocrine tumours.

Neuroendocrine tumours arising within the digestive system are classified as well-differentiated [slower growing] (traditionally referred to as carcinoid tumours when they arose in the tubular gastrointestinal tract and pancreatic neuroendocrine [islet cell] tumours when they arose in the pancreas or, in the case of gastrinomas, in the proximal portion of the duodenum), or poorly differentiated neuroendocrine carcinomas [fast growing] which are generally high grade and can resemble small cell or large cell neuroendocrine carcinoma of the lung.

Table 4: Nomenclature and classification for digestive system neuroendocrine tumours

Pulmonary carcinoids as a whole are well differentiated as opposed to small cell lung carcinoma and large cell neuroendocrine carcinoma, with typical carcinoids sharing some similarities to Grade 1 NETs and atypical carcinoids showing some similarities to Grade 2 NETs of the gastroenteropancreatic tract.

Typical carcinoid has fewer than 2 mitoses/2mm2 and absence of necrosis, and atypical carcinoid has 2-10 mitoses/2mm2 and/or foci of punctate necrosis.  Small cell lung carcinoma and large cell neuroendocrine carcinoma have more than 10 mitoses/2 mm2 and extensive necrosis.

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