Neuroendocrine tumours (NETs) (historically called APUDomas) represent a wide spectrum of disease. They consist of a large heterogeneous group of malignancies that are derived from embryonic neural crest tissue found in various organ such as the hypothalamus, pituitary gland, thyroid gland, adrenal medulla, and gastrointestinal tract.
The spectrum of neuroendocrine tumours range from:
carcinoid tumour: arising from enterochromaffin cells and can occur at various sites such as thymus, lung, ovary
phaeochromocytoma: typically occurs in the adrenals but can also occur in extra-adrenal sites
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location dependant entities
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abdomen
thorax/lung: pulmonary neuroendocrine tumours
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endocrine glands
pituitary: pituitary neuroendocrine tumour (pituitary adenoma)
thyroid: medullary thyroid tumours
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Pathology
They can also be divided by their biochemical behaviour as functioning or non-functioning, by their aggressiveness as slow-growing and more aggressive lesions and so on.
Because of secretory products by amine precursor uptake and decarboxylation (APUD) they were historically known as APUDomas.
Genetics
Mostly occur sporadically, some are linked to multiple endocrine neoplasia syndromes.