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B10. Surgical treatment of adrenal tumors

Adrenal tumours range from asymptomatic to potentially causing lots of unusual symptoms. The most common ones are:

Treatment

Adrenal surgery is mostly performed laparoscopically. Large tumours (> 10 cm, mostly cancers) may be operated in an open fashion instead.

Laparoscopic adrenalectomy (removing the entire gland) is indicated for:

Before surgical treatment of phaeochromocytoma, the patient should receive alpha blocker followed by beta blocker, to prevent hypertensive crisis due to surgical manipulation of the tumour. Surgical removal of phaeochromocytoma involves the “no-touch” technique to minimise the risk of catecholamine-release-induced hypertensive crisis intraoperatively.

Contraindications to laparoscopy:

  • Large tumours (> 10 cm)
  • Cortical carcinoma
  • Malignant phaeochromocytoma

Enucleation refers to removal of the mass while leaving the rest of the gland intact. This is used for bilateral tumours (as one needs at least one gland to survive) or unilateral tumours with massive hormone production.

Adrenal adenoma

Adrenal adenomas are small (1 – 5 cm), yellow, soft benign adrenal tumours. Only a small percentage of them are functional (hormone-secreting), while the majority are non-functional.

Adrenal tumours are often discovered incidentally on CT imaging, giving them the nickname adrenal incidentaloma. In most cases, these incidentalomas are harmless non-functional adrenal adenomas. Incidentalomas are found on 0,3 – 5% of abdominal CT scans and are therefore quite common.

These tumours may grow or become malignant, and they may worsen other endocrine diseases like diabetes mellitus, osteoporosis, or hypertension. For these reasons, the patient must be evaluated for the likelihood for it being malignant and whether it’s hormonally active (Cushing syndrome, phaeochromocytoma, aldosteronoma).

Evaluation

Certain CT characteristics increase the risk of the incidentaloma being adrenal carcinoma. Benign findings include small size, low density (< 10 HU) due to containing mostly adipose tissue, smooth border, rapid contrast washout. Malignant findings include irregular shape, inhomogeneous density, and delayed contrast washout. MRI with in-phase and out-phase can also help distinguish it from carcinoma.

Adrenal washout refers to the rate of intravenous CT contrast washout of the adrenal gland, which can help distinguish adenoma from other pathologies:

  • > 60% absolute washout (AWO) or > 40% relative washout (RWO) makes adenoma most likely
  • < 50% washout indicates adrenal metastasis

If phaeochromocytoma is suspected, 24-hour urinary metanephrines should be measured. Patients may undergo dexamethasone suppression test to detect subclinical Cushing syndrome.

Treatment

For indications of treatment, see adrenal tumours.


Adrenal carcinoma

Adrenal carcinomas are adrenal tumours which are usually larger (up to 20 cm) and aggressive malignant tumors. They usually contain necrosis or haemorrhage. They tend to invade the adrenal veins and inferior vena cava. These cancers are quite rare.


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.