Are Adrenal Tumors Common?
Adrenal tumors are common: they are found on a few percent of abdominal CT scans in adults, and more often with increasing age. The most common adrenal problem is the development of a benign, non-cancerous tumor inside the adrenal gland, often called an adrenal adenoma or adrenal nodule. When you have a tumor of the adrenal gland, the first thing you need to figure out is whether it’s overproducing any adrenal hormones. These hormones are cortisol, aldosterone and catecholamines (adrenaline and noradrenaline, also known as epinephrine and norepinephrine), and, more rarely, sex-steroid hormones (androgens and estrogens). A tumor that is overproducing any of these hormones is called a "functional" (or endocrine active) tumor. It is called a functional tumor because it is overfunctioning, i.e. overproducing hormones.
A functional adrenal tumor producing excess aldosterone, causing primary aldosteronism (Conn's syndrome).
Functional Adrenal Tumors are Common and Produce Too Much Hormone, Making You Sick
Adrenal tumors that produce hormones are called "functional" adrenal tumors. That means they make the same hormones as a normal adrenal gland--but they just produce too much of the hormone. A tumor that is overproducing cortisol causes adrenal hypercortisolism (AHC), formerly called MACS (mild autonomous cortisol secretion) or subclinical Cushing syndrome; severe AHC is adrenal Cushing syndrome. AHC is the most common hormone excess found in adrenal tumors. A tumor that is overproducing aldosterone causes primary aldosteronism (PA), also known as primary hyperaldosteronism or Conn's syndrome. A tumor that is overproducing catecholamines (adrenaline-type hormones) is called a pheochromocytoma.Most functional adrenal tumors are benign. It is important for you to understand that most functional adrenal tumors are benign (non-cancerous). That means, if your adrenal tumor produces too much cortisol or aldosterone, it is almost always benign. Pheochromocytomas are a special case: most never spread, but all of them are considered to have the potential to do so, which is why lifelong follow-up is needed. In the first picture on this page, the round tumor is easily seen within the triangle-shaped adrenal gland that Dr. Carling removed from a 38-year-old woman. The round tumor measured 1.5 cm (a little over half an inch) in diameter and was producing too much aldosterone. This woman had high blood pressure and low potassium in her blood due to excess aldosterone production. This is primary aldosteronism (Conn's syndrome). We operate on people with PA and tumors like this every week. Most of these operations (Mini Back Scope Adrenalectomy; MBSA) typically take about 20 minutes and the patient has only a few small Band-Aids on their lower back.
Typical small Band-Aids at the patient's flank after a Mini Back Scope Adrenalectomy (MBSA) for a functional adrenal tumor causing primary aldosteronism (Conn's syndrome).
IMPORTANT: If the adrenal tumor has overproduction of sex-steroid hormones, this often occurs in the setting of a cancerous tumor, so it is very important to know which hormones are being produced by the adrenal tumor.
Do Functioning Adrenal Tumors Need to be Removed?
In most cases, yes. A functional tumor should almost always be removed, not primarily because of the concern for cancer, but because of the damage caused to the body by the excess of these "toxic" hormones. Surgery (adrenalectomy) is the only treatment that can cure a hormone-producing tumor, and we believe it is underused. There are exceptions: mild primary aldosteronism, or aldosterone excess coming from both adrenal glands, often responds well to medication, and in mild AHC the decision is individualized, based on your cortisol-related health problems (such as high blood pressure, diabetes or pre-diabetes, osteoporosis and weight gain), your age, surgical risk and your preference. You can learn more about adrenal surgery on other pages of this website. Dr. Carling performs this operation almost every day.Steps to Take to Determine Treatment of an Adrenal Tumor
The first step is always to figure out whether the adrenal tumor is functional or not. This is done by a very careful history and physical exam by an experienced doctor and then a combination of blood and urine laboratory tests. Every adrenal mass needs a 1-mg overnight dexamethasone suppression test (a morning cortisol above 1.8 µg/dL is abnormal) together with ACTH and DHEA-S, aldosterone and renin if you have high blood pressure or low potassium, and plasma or urine metanephrines. Even if the tumor is nonfunctional (there is no evidence that the tumor is overproducing hormones) it still can be a potential problem.The second step is to determine whether the tumor is really arising from the adrenal gland or whether something else is going on in the vicinity of the adrenal gland. It could be a different kind of tumor that is just adjacent to the adrenal gland, but not arising from it. This is very important. Often radiological imaging is very helpful here. We have written much more about scans used for adrenal tumors in another section of this site.
The third step is very important and that is to ask whether the adrenal tumor is cancerous or noncancerous. That is, is it benign or malignant? What we worry about is adrenocortical carcinoma or a metastatic pheochromocytoma if the tumor is arising from the adrenal gland. Even if the tumor did not originate from the adrenal gland it could be a spread (metastasis) from another cancer into the adrenal gland. Again, CT scans, MRI and other scans of the adrenal gland can be helpful. Read more about the risk of cancer in adrenal tumors.
Does the Size of the Adrenal Tumor Matter?
The size of the adrenal tumor is very important for determining whether the tumor is potentially cancerous (malignant), or not. Very small tumors (meaning 1 to 2 cm; less than an inch) are almost never cancerous. However, larger tumors are much more frequently cancerous. As discussed above, an adrenal tumor of any size should almost always be removed if it is making excessive hormones. However, even if the tumor is not making too much hormone, we generally recommend removing tumors that have grown to more than 4 cm in an adult, unless the scan shows a clearly benign tumor.Recommendations: we generally recommend removing an adrenal tumor that is 4 cm (about 1.5 inches) or larger unless it is clearly benign on imaging (for example a lipid-rich adenoma measuring 10 Hounsfield units or less on a CT scan without contrast, a myelolipoma or a simple cyst). For younger patients, we would use a 3 cm (a little over 1 inch) cutoff. This is a general guide, and there are exceptions to this rule. This is why it is important for you to seek the advice of a surgeon who has extensive experience in adrenal gland surgery and treats adrenal tumors routinely.
The large adrenal gland cancer (13.5 cm; arrow) is shown on an MRI scan sitting on top of the left kidney.
It should be noted that size is not the only criterion for determining whether the tumor is benign or malignant. When we look at the imaging of the adrenal glands, whether it is a CT, MRI, nuclear medicine (MIBG, PET, etc) scan or other imaging study, we need to have a whole-person approach and evaluate all aspects of the tumor and the patient. We carefully analyze the imaging phenotype of the tumor. The imaging phenotype describes all aspects of what the tumor looks like on your scan and helps us determine the likelihood of cancer. It should be noted, however, this is far from a perfect science. In many cases, we can never know for sure whether the tumor is cancerous, or not, short of removing it via surgery.
Experience counts when examining scans of adrenal tumors. What we look for on an imaging study (like a CT scan) is a combination of more than a dozen criteria, giving us a total impression, called the "imaging phenotype". For instance, we carefully examine the size and the shape of the tumor. That means we will look at whether the borders are smooth or irregular, whether the margins (edges) are clear or unclear. On a CT scan without contrast, it is important to look at the level of attenuation. Essentially, this is a measure of how dense (or fat-containing) the tumor is based on measurements of what are called Hounsfield Units (HU). The lower the Hounsfield Units (lipid-rich; i.e. fatty) are, the more likely it is not a cancer, but rather a common adrenocortical adenoma. A tumor measuring 10 HU or less is a lipid-rich, benign adenoma. As you can see, it is very important for you to have an experienced adrenal surgeon who has seen hundreds or even thousands of these tumors and their scans so you can get the best treatment.
When the tumor is denser than this on the CT scan without contrast, a CT scan with contrast or an MRI can add information, for example whether the tumor is vascular (has a lot of blood flow) or not. Typically, benign adenomas are not very vascular, whereas more vascular tumors tend to be either a pheochromocytoma or a malignant tumor. On an MRI, tumors that look brighter (more intense) on certain images are more likely to be either cancers or pheochromocytomas.
We also look at the presence of necrosis (dying tissue), bleeding (hemorrhage), calcifications (calcium deposits) as well as the growth rate of the tumor in case the patient has had previous imaging of the adrenal glands. Remember that we want to review all your images. Yes, even if you had a scan for unrelated reasons 10 years ago, we want to review it to track the growth of the tumor.
Should the Adrenal Tumor or Adrenal Mass be Biopsied?
Almost never. A biopsy of the adrenal tumor is almost never helpful and it can cause significant problems. Important rule: an adrenal mass should almost never be biopsied. In fact, it can be very dangerous if the patient has a pheochromocytoma. The biopsy may produce an adrenergic crisis (read about adrenergic crisis in the pheochromocytoma and paraganglioma section of this site). If the patient has an adrenocortical carcinoma (adrenal cancer), the biopsy may spill tumor cells into the surrounding tissues. The tumor cells can then implant in these nearby tissues and cause local recurrence. Thus sticking needles into an adrenal tumor can decrease the chance of curing the patient. Also, a fine needle biopsy cannot reliably distinguish between a benign and malignant adrenocortical tumor, so it is an invasive test that rarely changes management. If your doctor wants to biopsy your adrenal tumor, ask why, and consider a second opinion--you are welcome to give us a call. The only time to consider a biopsy of an adrenal tumor is if the patient has another cancer, typically of the lung, kidney, breast, colorectal or melanoma, and an adrenal metastasis is suspected. Even then, a pheochromocytoma must first be ruled out with a blood or urine test for metanephrines.Because we see this mistake regularly, we will say it again: if your doctor sends you for a fine needle biopsy of an adrenal tumor, ask whether the result would change your treatment and whether a pheochromocytoma has been ruled out first.
A left adrenocortical cancer undergoing a CT-guided biopsy. This should not be performed. The only time to consider a biopsy of an adrenal tumor is if the patient has another cancer and an adrenal metastasis is suspected.
The rule is to almost never biopsy an adrenal tumor. As with all rules, though, there are some rare exceptions: a suspected metastasis from another cancer, as described above, and, less commonly, a suspected infection of the adrenal gland. Now you understand why patients with adrenal tumors should be seen by expert surgeons who have extensive experience with adrenal tumors. It can be somewhat tricky to know in advance of surgery whether the adrenal mass is cancerous, or not. Fortunately, the vast majority of adrenal tumors turn out to be benign. It is important to understand that sometimes surgery (adrenalectomy) is indicated just to prove that the adrenal tumor is not cancerous.
Read about the Mini Back Scope Adrenalectomy (MBSA), which is our preferred operation and is used for more than 95% of our operations.
Last updated October 2026.