Adrenal Adenoma Found: Surgery or Monitoring?

When an adrenal mass is removed

Surgery is usually discussed when the mass produces excess hormones or when the scans raise suspicion of a malignant tumor. The decision is made after hormone testing and CT, not simply because something was found. Whether surgery is appropriate is judged by the likelihood of malignancy, the degree of hormone excess, age, general health and the person’s own preferences^[1]. Surgery is usually discussed in these situations:

• excess aldosterone from one adrenal gland. The side is not determined by CT alone: the adenoma seen on a scan is not always the source of the hormone, so blood is usually sampled from the veins of both adrenal glands. If the excess is one-sided and the person is able and willing to have surgery, an operation is offered; otherwise medication that blocks the action of aldosterone is prescribed^[3];
• overt cortisol excess (Cushing’s syndrome) when its source is a tumor in one adrenal gland^[4];
• mild cortisol excess without overt signs of Cushing’s. It is detected with a 1 mg dexamethasone suppression test and confirmed with further tests. Surgery is discussed on an individual basis if related conditions are already present, such as high blood pressure or type 2 diabetes^[1];
• a suspicious CT appearance: a mass of 4 cm or more that is also inhomogeneous or has a density above 20 Hounsfield units on non-contrast CT. With this combination the risk of malignancy is high enough for surgery to be the usual choice^[1]. Other indeterminate masses are discussed at a multidisciplinary tumor board and investigated further if needed.

Pheochromocytoma is a separate case. It is not an adenoma but a different adrenal tumor that releases adrenaline and noradrenaline. It can look similar on CT, so if a mass lacks the typical features of an adenoma, it is ruled out with metanephrine tests. A pheochromocytoma is removed after mandatory preparation with medication^[5].

When surgery is not needed

When the adenoma does not produce excess hormones and looks typically benign on CT. A homogeneous mass with a density of 10 Hounsfield units or less on non-contrast CT is benign regardless of size and needs no further imaging^[1]. An asymptomatic, nonfunctioning one-sided mass with clearly benign features is usually not operated on^[1].

Observational data support this. A meta-analysis of 32 studies followed 4,121 patients with nonfunctioning adenomas or mild cortisol excess who were managed without surgery, for more than four years on average. Over that time the masses grew by 2 mm on average, growth of 10 mm or more occurred in only 2.5% of patients, and no adrenal cancer was recorded^[2]. Overt hormone excess developed in fewer than 0.1% of patients, and mild cortisol excess in 4.3% of those whose adenoma was initially nonfunctioning^[2].

These data concern selected patients with nonfunctioning adenomas or mild cortisol excess, not any adrenal mass, and they do not mean the risk is zero. But they explain well why the international guideline advises against operating on a typical nonfunctioning adenoma.

How people are monitored if they are not operated on

It depends on what the CT and tests showed.

• A typical benign adenoma without hormone excess. No repeat imaging is needed. Repeating hormone tests is usually unnecessary unless new symptoms appear or related conditions get worse^[1].
• An indeterminate mass that is not being operated on for now. CT or MRI is repeated after 6–12 months. If the mass has grown by more than 20% and by at least 5 mm, surgery is considered^[1].
• Mild cortisol excess. Blood pressure, blood sugar and other related conditions are assessed every year and treated^[1]. In the meta-analysis mentioned above, high blood pressure, obesity and type 2 diabetes developed and worsened more often in these patients, and new cardiovascular events were seen in 15.5% compared with 6.4% of those with a nonfunctioning adenoma^[2].

Is it true that adenomas under 4 cm are left alone?

No, size on its own decides nothing. A small adenoma that produces aldosterone or cortisol may need surgery. And a homogeneous mass with a density of 10 Hounsfield units or less on non-contrast CT is benign regardless of size^[1].

Size matters in combination with other features: a mass of 4 cm or more that is also inhomogeneous or has a density above 20 units on non-contrast CT is considered suspicious enough for surgery^[1]. Whether it is the left or right adrenal gland does not affect the indication for surgery.

Who treats an adrenal adenoma?

Usually several specialists together. An endocrinologist orders and interprets the hormone tests, a radiologist reports the CT, and a surgeon who performs adrenal surgery operates. The guideline advises discussing every mass without clearly benign features at a multidisciplinary tumor board^[1].

Adrenal surgery is not planned without hormone testing: what the tumor produces determines the indications, the preparation and the care after the operation. Complex cases, such as suspected cancer, an adrenal metastasis or tumors on both sides, are reviewed at our tumor board.

How the adrenal gland is removed and what happens afterwards

Most often laparoscopically, through a few small incisions. When the patient and tumor allow it, minimally invasive removal is recommended over open surgery because it causes fewer complications. The approach can be through the abdomen or from the back^[4]. When adrenocortical carcinoma is suspected, open surgery is usually preferred: the tumor is removed completely without breaching it, en bloc with surrounding tissue if needed^[4]. I perform these operations together with a team of surgical oncologists. How they are done is described on the adrenal tumor surgery page.

What happens after surgery depends on what the tumor was producing:

• after removal of a cortisol-producing tumor, the other adrenal gland may work less well for a while. With overt Cushing’s syndrome, everyone is given the hormone during and after surgery. With mild cortisol excess, the European guideline also advises giving the hormone during surgery, while experienced centers may instead test whether it is needed after surgery, provided there is close monitoring. The hormone is stopped only after it is confirmed that the adrenal function has recovered^[1][4];
• after removal of a pheochromocytoma, lifelong follow-up is advised to catch any recurrence in time^[5];
• treatment of aldosteronism, by surgery or medication, aims to improve blood pressure control and reduce the risk of cardiovascular complications^[3].

One healthy adrenal gland is usually enough for a normal life.

What to do if an adrenal adenoma is found

1. Collect the images and the density reportYou need a non-contrast CT with the density of the mass in Hounsfield units. Get the images on a disc.
2. Have hormone testingAn endocrinologist orders and interprets it. But even with normal hormones, surgery may be offered if the CT is suspicious.
3. If surgery is not advised, follow the monitoring planAnd treat blood pressure and blood sugar, especially with mild cortisol excess.
4. If surgery is advised, show the results to a surgeonSend your CT and hormone tests: the online consultation is free. We discuss the treatment plan with you after a full workup and a tumor board review.

Sources

1. Fassnacht M, Tsagarakis S, Terzolo M, et al. European Society of Endocrinology clinical practice guidelines on the management of adrenal incidentalomas, in collaboration with the European Network for the Study of Adrenal Tumors. Eur J Endocrinol. 2023;189(1):G1–G42. PMID 37318239
2. Elhassan YS, Alahdab F, Prete A, et al. Natural History of Adrenal Incidentalomas With and Without Mild Autonomous Cortisol Excess: A Systematic Review and Meta-analysis. Ann Intern Med. 2019;171(2):107–116. PMID 31234202
3. Adler GK, Stowasser M, Correa RR, et al. Primary Aldosteronism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2025;110(9):2453–2495. PMID 40658480
4. Yip L, Duh QY, Wachtel H, et al. American Association of Endocrine Surgeons Guidelines for Adrenalectomy: Executive Summary. JAMA Surg. 2022;157(10):870–877. PMID 35976622
5. Lenders JW, Duh QY, Eisenhofer G, et al. Pheochromocytoma and paraganglioma: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2014;99(6):1915–1942. PMID 24893135

This article is for general information and does not replace a consultation: the decision on surgery is based on your own scans and test results.