• Pheochromocytoma (pheo) is a catecholamine-producing tumor arising from the chromaffin tissues of the sympathetic nervous system
  • Origin from the adrenal medulla or sympathetic ganglia:
    • 80% solitary adrenal (usually the right side)
    • 10% bilateral
    • 10% extra-adrenal in location:
      • Abdominal, within mesenteric ganglia (86%)
      • Thorax (10%), neck (3%), bladder (1%)
    • 10% malignant
  • Incidence:
    • 0.2–0.4% of hypertensive patients, but higher proportion of patients with severe hypertension
    • 2–8/million population per year
    • Peaks in decades 3–5, 10% in children
    • Male = female, average age 40–50 yr
    • In about 1/2 of the cases, the diagnosis is made postmortem
    • 10% asymptomatic, incidental on CT
  • Genetics:
    • Inherited form 10–20%, autosomal dominant
    • More likely to be bilateral, extra-adrenal and malignant
    • Usually associated with multiple endocrine neoplasia (MEN) 2A, less so with MEN 2B or von Hippel–Lindau (VHL) disease:
      • MEN 2A (medullary thyroid carcinoma [CA], pheo, and hyperparathyroidism)
      • MEN 2B (medullary thyroid CA, pheo, oral mucosal neuromas, skeletal and bony abnormalities)
      • VHL (hemangioblastomas of retina and CNS, pancreas and renal cysts, and pheo)
    • Other associated diseases: Neurofibromatosis, tuberous sclerosis, Sturge–Weber syndrome, paragangliomas of the neck


  • The tumor synthesizes and stores catecholamines in the same manner as the normal adrenal medulla
  • Tumors predominantly secrete norepinephrine, and to a lesser extent epinephrine (some tumors are epinephrine predominant, in which hypotensive episodes are characteristic) and dopamine
  • Paroxysmal release of catecholamines:
    • Spontaneously due to changes in blood flow or tumor necrosis
    • Direct pressure on the gland from external forces (trauma, exercise)
    • Precipitation of release (opiates, glucagon, metoclopramide, steroids, foods with tyramine, iodinated contrast media)
    • Augmentation of catecholamine effect (tricyclic antidepressants [TCAs], β-blockers, sympathomimetics)

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