Pheochromocytoma is the most common tumor of the adrenal medulla in adults as compared to Neuroblastoma, which is most common in children. Pheochromocytoma causes episodic hypertension; neuroblastoma does not.
Pheochromocytoma is derived from chromaffin cells (arise from neural crest). Most tumors secrete epinephrine, NE, and dopamine and can cause episodic hypertension. Urinary vanillylmandelic acid, VMA (a breakdown product of norepinephrine) and plasma catecholamines are elevated. Associated with neurofibromatosis, Multiple Endocrine Neoplasia (MEN types 2A and 2B.)
Signs and Symptoms:
The signs and symptoms of a pheochromocytoma are those of sympathetic nervous system hyperactivity, including:
- Skin sensations
- Flank pain
- Elevated heart rate
- Elevated blood pressure, including paroxysmal (sporadic, episodic) high blood pressure, which sometimes can be more difficult to detect; another clue to the presence of pheochromocytoma is orthostatic hypotension (a fall in systolic blood pressure greater than 20 mmHg or a fall in diastolic blood pressure greater than 10 mmHg upon standing)
- Anxiety often resembling that of a panic attack
- Diaphoresis (excessive sweating)
- Headaches – most common symptom
- Weight loss
- Localized amyloid deposits found microscopically
- Elevated blood glucose level (due primarily to catecholamine stimulation of lipolysis (breakdown of stored fat) leading to high levels of free fatty acids and the subsequent inhibition of glucose uptake by muscle cells. Further, stimulation of beta-adrenergic receptors leads to glycogenolysis and gluconeogenesis and thus elevation of blood glucose levels).
Treatment for Pheochromocytoma:
α-antagonists, especially phenoxybenzamine, a nonselective, irreversible α-blocker. Phenoxybenzamine is used before removing the tumor, since high levels of released catecholamines will not be able to overcome blockage, followed by surgery to remove the tumor.
Episodic hyperadrenergic symptoms (5 P’s):
- Pressure (elevated blood pressure)
- Pain (headache)
- Palpitations (tachycardia)