Pheochromocytoma

Posted by e-Medical PPT
A tumor of chromaffin cells that secrete catecholamines (epinephrine or norepinephrine) 
Typically benign, it is a well-encapsulated, lobular, vascular tumor that can weigh between 70-3600 g
Location is in the adrenal medulla in 80% of cases
They may also be found in extra-adrenal tissues derived from neural crest cells (called paraganglionomas)

Pathophysiology: medullary function 
Adrenal medulla: 80% epinephrine, 20% norepinephrine
Hormones stored in secretory cell granules
Release of hormones by preganglionic neurons

Catecholamine synthesis
Tyrosine hydroxylation
Decarboxylation of DOPA to dopamine
Hydroxylation to norepinephrine
Methylation of NE to epinephrine via PMNT

Epidemiology 
Rare neoplasm
Rare cause of secondary hypertension (<0.2% all causes HTN)
Seldom diagnosed (10% discovered incidentally)
A retrospective study from the Mayo Clinic- in 50% of cases, the diagnosis was made at autopsy (Beard, 1983).
Series by Fogerty, et. al., only 1 out of 300 patients evaluated for suspected pheochromocytoma were confirmed to carry the diagnosis.

Classic Association with MEN-2
 MEN-2A (Sipple’s Syndrome)
    Autosomal dominant
    MTC, pheochromocytoma, parathyroid hyperplasia
 MEN-2B
    Autosomal dominant
    MTC, pheochromocytoma, ganglioneuromas, prototypical facies
50% patients manifest symptoms of pheochromocytome
33% demonstrate HTN

Familial Association- higher incidence of pheochromocytoma
 VonHippel-Lindau Disease
 Von Recklinghausen’s Disease
 Sturge-Weber Syndrome
 Tuberous Sclerosis

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