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- A pheochromocytoma is a rare neuroendocrine tumor arising from the adrenal or extra-adrenal chromaffin tissue and, less commonly, the sympathetic ganglia.
- These tumors are catecholamine-producing: Norepinephrine (NE) > epinephrine (EPI) >>> dopamine (DA).
- System(s) affected: Endocrine; Nervous; Cardiovascular
- Synonym(s): Chromaffin tumors; Paragangliomas
- 500–1,000 cases/yr diagnosed in the US
- <0.2% of people with severe hypertension (HTN)
- 1:6,500–1:2,500 in Western countries
- Affects all genders and ages; usually diagnosed in 4th–5th decade of life, familial cases diagnosed 1 decade earlier
- Familial pheochromocytoma
- Familial paraganglioma
- Multiple endocrine neoplasia type 2 (MEN-2)
- von Hippel-Lindau disease (VHL)
- von Recklinghausen neurofibromatosis type 1 (NF-1)
Genetic testing is recommended; genes identified in the pathogenesis:
- Rearranged during transfection (RET) proto-oncogene
- von Hippel-Lindau disease tumor suppressor gene (VHL)
- Neurofibromatosis type 1 tumor suppressor gene (NH 1)
- Genes encoding 4 succinate dehydrogenase complex (SDH) subunits
- Gene encoding the enzyme responsible for flavination of the SDHA subunit
- Tumor suppressor TMEM127 gene
Pheochromocytoma is a tumor that releases catecholamines into the circulation. Catecholamines interact with adrenergic receptors to produce various effects that could induce severe lethal cardiovascular and cerebrovascular complications:
- Stimulation of α1 receptors (NE > EPI) causes smooth muscle constriction resulting in high BP (arteriolar vasoconstriction).
- Stimulation of α2 receptors (EPI > NE) causes smooth muscle contraction, cardiac muscle relaxation, and inhibition of hormones, such as insulin, resulting in elevated blood glucose levels.
- Stimulation of β1 receptors (EPI = NE) causes heart muscle contraction resulting in increased heart rate.
- Stimulation of β2 receptors (EPI >> NE) causes smooth muscle relaxation.
- In 80% of cases, it is a sporadic disease of unknown etiology.
- In 20% of cases, it has familial origin and is a component of 1 of the following 4 autosomaldominant diseases:
- Hereditary paraganglioma syndrome (PGL)
- Tumor location:
- 80% are solitary and unilateral.
- 20% are divided between bilateral lesions and extra-adrenal masses (organ of Zuckerkandl, neck, mediastinum, abdomen, pelvis)
Commonly Associated Conditions
- Multiple endocrine neoplasia type IIA (medullary thyroid carcinoma and primary hyperparathyroidism)
- Multiple endocrine neoplasia type IIB (medullary thyroid carcinoma and mucosal neuromas)
- von-Hippel-Lindau disease (retinal angiomas, cerebellar hemangioblastomas, renal cysts, carcinomas, pancreatic cysts, epididymal cystadenomas)
- Neurofibromatosis type 1
- Sturge-Weber syndrome
- Tuberous sclerosis
- Carney syndrome (gastric epithelioid leiomyosarcoma, pulmonary chondroma, extra-adrenal paraganglioma)
- Familial paraganglioma
- Renal artery stenosis