Write a short note on Phaeochromocytoma.

The Concept

A phaeochromocytoma is a catecholamine-secreting tumour of the adrenal medulla (arising from chromaffin cells). Its entire clinical picture and its dangers come from the episodic release of adrenaline and noradrenaline, which cause paroxysmal, severe sympathetic overactivity. It is often summarised by the 'rule of 10s': roughly 10% are bilateral, 10% extra-adrenal (paraganglioma), 10% malignant, and 10% familial (associated with men 2, von Hippel-Lindau and neurofibromatosis).

Clinical Features

The classic triad is episodic headache, palpitations and profuse sweating, occurring together with paroxysmal (or sustained) hypertension — the hypertension may be severe and difficult to control, and can occur in dangerous crises. Other features include tremor, pallor, anxiety and weight loss. It is an important surgically-correctable cause of hypertension, especially in a young patient or one with resistant hypertension.

Diagnosis, Localisation & Management

Diagnosis is biochemical — measuring the catecholamine breakdown products, plasma or 24-hour urinary metanephrines (more reliable than catecholamines themselves). The tumour is then localised with CT or MRI of the adrenals, and functional imaging (MIBG scan) can find extra-adrenal or metastatic tumour. Treatment is surgical excision (adrenalectomy), but the preparation is the critical, examinable point.

Hypertensive Crisis & Anaesthetic Risk

The great danger of an unrecognised phaeochromocytoma is a catecholamine crisis — precipitated by anaesthesia, surgery, or handling the tumour — causing extreme hypertension, arrhythmia, myocardial infarction or stroke. This is why any patient undergoing surgery for it (or for associated men 2 thyroid disease) must be fully alpha-blocked and volume-repleted for 1–2 weeks beforehand, and why the tumour is handled minimally and the venous drainage ligated early during excision.

Pre-operative Preparation in Detail

The preparation of a phaeochromocytoma for surgery is a classic viva topic. The patient is alpha-blocked first with phenoxybenzamine for 1–2 weeks, allowing the chronically constricted vasculature to relax and the contracted blood volume to re-expand (encouraged by a liberal salt/fluid intake); only once alpha-blockade is established is a beta-blocker added to control any reflex tachycardia. Giving a beta-blocker first is dangerous because blocking beta-mediated vasodilatation leaves alpha-mediated vasoconstriction unopposed, precipitating a hypertensive crisis. Adequate preparation converts a hazardous operation into a safe one.

The Bottom Line

The examinable core is the alpha-before-beta rule: excise after full alpha-blockade (phenoxybenzamine) and volume repletion, adding a beta-blocker only afterwards, because beta-blockade first leaves alpha-vasoconstriction unopposed and can trigger a fatal hypertensive crisis — the single most important management point in the whole topic.

Alpha blockade must precede beta blockade or crisis may result.

• Phaeochromocytoma = catecholamine-secreting tumour of the adrenal medulla (chromaffin cells).
• 'Rule of 10s': 10% bilateral, extra-adrenal, malignant, familial (men 2, VHL, NF1).
• Episodic headache + palpitations + sweating with paroxysmal/sustained hypertension; surgically correctable hypertension.
• Diagnose with plasma/urinary metanephrines; localise with CT/MRI ± MIBG.
• Treat by adrenalectomy after alpha-blockade (phenoxybenzamine) first, then beta-blockade — never beta first (unopposed alpha → crisis).