Adrenal incidentaloma !

An adrenal lump found by chance on a scan done for another reason. Most are harmless, but each needs hormone tests and a check that it is not cancer.

Updated 2026-11-01

Structures involved

Tap one to see what it is and open it in 3D.

Why it happens

What it is

An adrenal mass, usually 1 cm or larger, discovered on imaging performed for a reason other than suspected adrenal disease. The two questions in every case are whether it secretes hormones and whether it is malignant.

Who gets it

Found in a few per cent of abdominal CT scans, and more often with age (over 5 to 7% of people older than 70). Its detection has risen with the wider use of CT in Colombia and the rest of Latin America. Most are benign non-functioning cortical adenomas.

Causes

Non-functioning adrenocortical adenoma (most common)
Adenoma with autonomous cortisol secretion (mild cortisol excess without full Cushing features)
Aldosterone-producing adenoma and pheochromocytoma
Adrenocortical carcinoma and metastases (lung, breast, kidney, melanoma, lymphoma)
Myelolipoma, cyst, haemorrhage and granulomatous infection (tuberculosis, histoplasmosis)

Risk factors

Older age
Obesity, type 2 diabetes and hypertension (associated with adenomas)
Known extra-adrenal cancer (raises the chance of metastasis)

Pathophysiology

Most incidentalomas are clonal benign growths of the adrenal cortex rich in intracellular lipid, which makes them low-density on unenhanced CT. Some secrete cortisol independently of ACTH; even modest excess raises the risk of hypertension, diabetes, osteoporosis and cardiovascular events. Malignant lesions are usually larger, lipid-poor and heterogeneous, and grow over time.

Classification

By function: non-functioning, autonomous cortisol secretion, primary aldosteronism, pheochromocytoma
By imaging: benign-appearing (homogeneous, 10 Hounsfield units or less on unenhanced CT) versus indeterminate
By size: under 4 cm versus 4 cm or more, which raises concern for carcinoma

Symptoms and signs

Usually none; found on a scan for abdominal pain, trauma or cancer staging
Subtle features of cortisol excess: weight gain, hypertension, hyperglycaemia, bone loss
Resistant hypertension or low potassium suggesting aldosterone excess
Episodes of headache, sweating and palpitations suggesting pheochromocytoma
Flank pain or weight loss with large or malignant masses

Diagnosis

Clinical: History and examination for hypertension, Cushing features, virilisation, adrenergic episodes and known cancer; review of the imaging that found the mass.
Tests: Every patient: 1 mg overnight dexamethasone suppression test for autonomous cortisol secretion and plasma or urine metanephrines for pheochromocytoma (metanephrines can be omitted if the mass is clearly lipid-rich adenoma on CT). Aldosterone-to-renin ratio if there is hypertension or low potassium. Sex steroid precursors if carcinoma is suspected. Biopsy is rarely needed and only after pheochromocytoma is excluded.
Imaging: Unenhanced CT is the key test: a homogeneous mass of 10 Hounsfield units or less is a benign adenoma. Indeterminate masses are assessed with contrast washout CT, chemical-shift MRI or FDG-PET.

Differential diagnosis

Adrenocortical carcinoma
Metastasis to the adrenal gland
Pheochromocytoma
Adrenal haemorrhage or cyst
Pseudo-adrenal masses: upper pole renal lesion, splenic lobule, vessel or gastric diverticulum

Goal of treatment

Identify the few masses that are malignant or hormonally active and treat them, while sparing the many benign non-functioning adenomas from unnecessary surgery and repeated tests.

Treatment

Surgical: Adrenalectomy, usually laparoscopic, for functioning tumours (pheochromocytoma, aldosterone-producing adenoma, overt Cushing syndrome), suspected carcinoma or indeterminate masses that grow; selected cases of autonomous cortisol secretion with related disease.
Medical: Preoperative alpha-blockade for pheochromocytoma; perioperative glucocorticoid cover after removal of a cortisol-secreting adenoma because the other adrenal is suppressed. Treatment of hypertension, diabetes and bone loss in non-operated patients with mild cortisol excess.
Follow-up: Benign-appearing small non-functioning adenomas need no further imaging. Indeterminate masses are re-imaged at about 6 to 12 months. Mild cortisol excess is reviewed for its metabolic complications.

Complications

Missed pheochromocytoma causing a hypertensive crisis during surgery or biopsy
Cardiometabolic disease from autonomous cortisol secretion
Adrenal insufficiency after removal of a cortisol-secreting adenoma
Delayed diagnosis of adrenocortical carcinoma or metastasis

Prognosis

Excellent for benign non-functioning adenomas, which rarely grow or become active. Prognosis is driven by the underlying lesion when it is a carcinoma or metastasis.

Test yourself

Think of the answer, then tap the question to see it.

Which two questions must be answered for every adrenal incidentaloma?

Is it hormonally active, and is it malignant?

Which unenhanced CT finding confirms a benign lipid-rich adenoma?

A homogeneous mass with attenuation of 10 Hounsfield units or less.

Which screening test detects autonomous cortisol secretion?

The 1 mg overnight dexamethasone suppression test.

Why must pheochromocytoma be excluded before adrenal biopsy or surgery?

Manipulation can release catecholamines and trigger a hypertensive crisis.

Add to my cards (4)

Educational information, not medical advice. For any symptom, see a health professional.

Sources: ESE Clinical Practice Guideline on the management of Adrenal Incidentalomas, in collaboration with the European Network for the Study of Adrenal Tumors (European Society of Endocrinology, 2023); Nonfunctional Adrenal Masses - Endocrinology - MSD Manual Professional Edition (MSD Manual Professional Edition, 2025).

← All conditions

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.

Adrenal arteries highlighted on the Durgical 3D model