Adrenal Adenoma

What an adrenal adenoma is

Each adrenal gland has two parts. The outer cortex makes cortisol (the stress hormone), aldosterone (which controls salt and blood pressure) and small amounts of androgens. The inner medulla makes adrenaline. An adenoma is a well-defined, benign lump of cortex cells. Most measure 1 to 4 cm.

Because modern CT and MRI scans are so detailed, adrenal nodules are found by chance in many people scanned for back pain, kidney stones or injuries. A lump found this way is called an adrenal incidentaloma. Most incidentalomas turn out to be adenomas.

Why adrenal adenomas appear

The exact reason is usually unknown. Contributing factors include:

• Age: they become more common with each decade and are rare in children.
• Genetic changes in adrenal cells: mutations in genes controlling cell growth or hormone production (such as KCNJ5 in aldosterone-producing adenomas or PRKACA in some cortisol-producing ones) occur within the tumor.
• Metabolic factors: they are found more often in people with obesity, type 2 diabetes and high blood pressure, although it is not always clear which comes first.
• Inherited syndromes in a small number of people, such as multiple endocrine neoplasia type 1, familial adenomatous polyposis or Carney complex.

Functioning vs nonfunctioning adenomas

Adrenaline-producing tumors are not adenomas. They are pheochromocytomas, from the medulla, but every incidentaloma is assessed to make sure it is not one.

Symptoms

Most adrenal adenomas cause no symptoms. When symptoms occur, they come from hormone excess:

• Cortisol excess: weight gain around the face, upper back and belly, thin skin, easy bruising, wide purple stretch marks, muscle weakness in the thighs and shoulders, high blood sugar, bone thinning, mood changes, irregular periods
• Aldosterone excess: high blood pressure, muscle weakness or cramps, tiredness, passing a lot of urine, palpitations from low potassium

A very large adenoma can rarely cause a dull ache in the flank or back.

Diagnosis

Two questions guide every assessment: is it benign? and does it make hormones?

Imaging

• Unenhanced CT: benign adenomas contain fat, so they appear low density. A homogeneous nodule measuring 10 Hounsfield units or less is almost certainly benign, and current European guidelines say no further imaging is needed.
• Washout CT or chemical-shift MRI: for nodules that are not clearly benign on plain CT.
• Size: lesions larger than 4 cm, irregular or growing ones raise concern for adrenocortical cancer or metastasis.

Hormone tests

• 1 mg overnight dexamethasone suppression test: for everyone with an incidentaloma, to detect cortisol excess.
• Aldosterone-to-renin ratio: for anyone with high blood pressure or low potassium.
• Plasma or urine metanephrines: to exclude pheochromocytoma when the CT does not show a clearly benign adenoma.
• Sex hormones if there are signs of androgen excess or the tumor looks suspicious.

Treatment

Watchful approach

Nonfunctioning adenomas with a clearly benign appearance usually need no surgery and, under current guidelines, no repeated scans. People with mild autonomous cortisol secretion are checked yearly for high blood pressure, diabetes and bone health, and these are treated.

Surgery

Laparoscopic (keyhole) adrenalectomy is recommended for:

• adenomas causing Cushing's syndrome
• aldosterone-producing adenomas, after adrenal vein sampling confirms the side
• selected cases of mild cortisol excess with worsening diabetes, blood pressure or bones, especially in younger people
• tumors with suspicious features or significant growth

Most people go home in 1 to 3 days. After removing a cortisol-producing adenoma, the other gland may be temporarily suppressed, so steroid replacement is needed for months until it recovers.

Medicines

For people who cannot have surgery, aldosterone blockers such as spironolactone or eplerenone treat aldosterone excess. Medicines that block cortisol production are used occasionally.

Outlook

Adrenal adenomas are benign and almost never become cancer. Removing a hormone-producing adenoma often improves or cures high blood pressure, low potassium and Cushing's features. Nonfunctioning adenomas rarely change over time.

Frequently asked questions

Why do adrenal adenomas appear?

Most appear without a clear cause, from genetic changes within adrenal cells that build up with age. They are more common in older adults and in people with obesity, diabetes and high blood pressure. A few are linked to inherited syndromes.

Are adrenal adenomas dangerous?

Most are not. They are benign and usually make no hormones. Those that produce cortisol or aldosterone can harm the heart, blood vessels, blood sugar and bones over time, which is why hormone testing is recommended for every adrenal nodule.

Does an adrenal adenoma need to be removed?

Only some. Surgery is advised if the adenoma produces excess hormones that cause problems, or if it looks suspicious or is growing on scans. Small, benign-looking, nonfunctioning adenomas are usually left alone.

What size of adrenal adenoma is concerning?

Doctors look closely at adrenal masses larger than 4 cm, because the chance of cancer rises with size. Appearance matters more than size: a nodule that is low density on unenhanced CT is benign in almost all cases.

Can an adrenal adenoma cause anxiety or panic attacks?

Adrenal adenomas rarely cause anxiety. Episodes of pounding heartbeat, sweating, headache and anxiety are more typical of a pheochromocytoma, a different adrenal tumor. Cortisol excess can cause mood changes, irritability and depression.