Symptoms and signs
Pheochromocytomae occur most often during young-adult to mid-adult life. Less than 10% of pheochromocytomas are malignant (cancerous).
These tumors can form a pattern with other endocrine gland cancers which is labelled multiple endocrine neoplasia. Pheochromocytoma is listed within the groups MEN 2a and MEN 2b.
The signs and symptoms of a pheochromocytoma are those of sympathetic nervous system hyperactivity: elevated heart rate and blood pressure and anxiety often resembling that of a panic attack.
One diagnostic test for a pheochromocytoma is to administer clonidine (Catapres®), a centrally-acting alpha-2 agonist used to treat high blood pressure. Clonidine mimics catacholamines in the brain, causing it to reduce the activity of the sympathetic nerves controlling the adrenal medulla. A healthy adrenal medulla will respond to clonidine by reducing catacholamine production; the lack of a response is evidence of pheochromocytoma. Another test is for the clinician to press gently on the adrenal gland. A pheochromocytoma will often release a burst of catacholamines, with the associated signs and symptoms quickly following.