Phaeochromocytoma

Phaeochromocytoma is an adrenal tumour of the adrenal medulla. They originate from the catecholamine-producing chromaffin cells of the adrenal medulla and therefore can produce catecholamines in most cases. They can be benign or malignant. They’re most commonly small, circumscribed lesions, but they can be large, haemorrhagic masses as well. Phaeochromocytomas are considered malignant only if they’re locally aggressive or metastatic. Phaeochromocytomas are quite rare.

Pheochromocytoma is a very convenient type of tumor because it follows something called the “10 percent rule”. Here’s how the rule works:

• 10% of cases of pheochromocytoma occur bilaterally (90% occur unilaterally)
• 10% of cases are familiar (90% are sporadic) – as part of MEN type II or other syndromes
• 10% of cases are malignant (90% are benign)
• 10% of cases are extra-adrenal, often in sympathetic ganglia (90% are in the adrenal medulla)
• 10% of cases occur in children (90% occur in adults)

Clinical features

Pheochromocytomas usually only secrete catecholamines in episodes and not constantly. This causes paroxysmal hypertensive crises, with systolic pressures reaching even 300 mmHg. These episodes are characterised by throbbing headache, sweating, palpitations and anxiety. They may also cause complications such as haemorrhagic stroke, rupture of aneurysms, myocardial infarct and aortic dissection.

Diagnosis and evaluation

Diagnosis of pheochromocytoma is based on the presence of high levels of catecholamines and catecholamine breakdown products like VMA and HVA in a 24-hour urine sample.

Treatment

For indications of treatment, see adrenal tumours.