Phaeochromocytoma

Question 1

Aetiology of phaechromocytoma

Answer 1

• tumour of the chromaffin cells that secretes unregulated and excessive amounts of adrenaline

25% are familial and associated withmultiple endocrine neoplasia type 2(MEN 2).

There is a10% ruleto describe the patterns of tumour:

• 10% bilateral
• 10% cancerous
• 10% outside the adrenal gland

Question 2

Pathophysiology of Phaeochromocytoma

Answer 2

• adrenalineis produced by the chromaffin cells in theadrenal medulla of theadrenal glands
• Aphaeochromocytoma is a tumour of thechromaffin cells that secretes unregulated and excessive amounts of adrenaline.
• Adrenaline is a catecholamine hormone and neurotransmitter that stimulates the sympathetic nervous system and is responsible for the “fight or flight” response.
• In patients with aphaeochromocytomathe adrenaline tends to be secreted in bursts giving periods of worse symptoms followed by more settled periods.

Question 3

Signs and symptoms phaeochromocytoma?

Answer 3

tend to fluctuate with peaks and troughs relating to periods when the tumour is secreting adrenaline.

• Anxiety
• Sweating
• Headache
• Hypertension
• Palpitations, tachycardia andparoxysmal atrial fibrillation

Question 4

Investigation/diagnosis

Answer 4

• 24 hrurinecatecholamines
• Plasma freemetanephrines

Measuring serumcatecholamines is unreliable as this will naturally fluctuate and it will be difficult to interpret the result. Measuring 24 hour urinecatecholaminesgives an idea of how muchadrenalineis being secreted by the tumour over the 24 hour period.

Adrenaline has a short half life of only a few minutes in the blood, whereasmetanephrines(a breakdown product of adrenaline) have a longer half life. This makes the level ofmetanephrinesless prone to dramatic fluctuations and a more reliable diagnostic tool.

Question 5

Treatment of phaeochromocytoma

Answer 5

• Alpha blockers (i.e.phenoxybenzamine)
• Beta blockers once established on alpha blockers
• Adrenalectomy to remove tumour is the definitive management

Patients should have symptoms controlled medically prior to surgery to reduce the risk of the anaesthetic and surgery