When a CT scan or MRI for something else-like back pain, a car accident, or a routine checkup-shows a lump on the adrenal gland, it’s called an adrenal incidentaloma. It’s not something you felt or noticed. It was found by accident. And while it sounds scary, the good news is that about 80% of these lumps are harmless, non-functioning adenomas that never need treatment. But the other 20%? They can be serious-hormone factories or even cancer. That’s why knowing how to evaluate them properly isn’t just important; it’s life-saving.
What Exactly Is an Adrenal Incidentaloma?
An adrenal incidentaloma is any adrenal mass larger than 1 cm found during imaging done for reasons unrelated to adrenal problems. These masses show up in about 2% of adults overall, but the chance jumps to over 7% if you’re over 70. That’s because older people get more scans-CTs, MRIs, ultrasounds-for other issues. The rise in imaging use over the last 30 years is exactly why these are now one of the most common endocrine findings in clinics today.The adrenal glands sit on top of each kidney. They make hormones like cortisol (your stress hormone), aldosterone (which controls blood pressure), and adrenaline (your fight-or-flight chemical). When a tumor forms there, it might not do anything… or it might start pumping out too much of one of these hormones. Or worse, it might be cancer.
Three Types of Adrenal Incidentalomas
Not all adrenal lumps are the same. They fall into three clear categories:- Functioning tumors: These make extra hormones. Examples include pheochromocytomas (adrenaline overproduction), cortisol-secreting tumors (Cushing’s syndrome), and aldosterone-producing adenomas (high blood pressure and low potassium).
- Malignant tumors: This includes primary adrenocortical carcinoma (a rare but aggressive cancer) or metastases from other cancers like lung or breast that spread to the adrenal gland.
- Benign non-functioning tumors: These are the most common-about 80% of cases. They don’t make hormones and don’t spread. Think adenomas, myelolipomas (fatty tumors), or simple cysts.
The goal of evaluation? Figure out which group your lump belongs to. That’s the only way to know if you need surgery, medication, or just a watch-and-wait approach.
Step 1: The First Scan-CT Without Contrast
The first test after finding a mass is usually an unenhanced CT scan. Why? Because it’s fast, cheap, and tells you a lot just by measuring density.Adrenal adenomas are often full of fat. Fat shows up as low density on CT, measured in Hounsfield units (HU). If the tumor’s density is below 10 HU, there’s a 70-80% chance it’s a benign adenoma. That’s a huge clue. No further testing may be needed if the mass is small, looks clean on the scan, and you have no symptoms.
But if the tumor is over 10 HU, looks irregular, has uneven edges, or shows signs of bleeding or calcification? That raises red flags. It doesn’t mean it’s cancer-but it means you need more tests.
Step 2: Hormone Testing-Don’t Skip This
No matter how benign the scan looks, you must check for hormone overproduction. Skipping this can lead to disaster.Pheochromocytoma is the most dangerous one to miss. These tumors make adrenaline and noradrenaline. If you go into surgery without knowing you have one, the stress of anesthesia can trigger a deadly surge in blood pressure. That’s why every single adrenal incidentaloma needs testing for pheochromocytoma. The test? Plasma-free metanephrines or a 24-hour urine collection for fractionated metanephrines. If those are high, you need an MRI and alpha-blocker treatment before any surgery.
Cortisol overproduction is trickier. It’s called autonomous cortisol secretion. You might not look like you have Cushing’s syndrome-no moon face or purple stretch marks-but your body is still getting too much cortisol. That increases your risk of diabetes, high blood pressure, heart disease, and bone loss. The test is a 1-mg dexamethasone suppression test. If your cortisol level stays above 1.8 μg/dL after the pill, you likely have subclinical Cushing’s. Around 5% of incidentalomas show this. Newer tests, like urinary steroid metabolomics, are now 92% accurate at catching it-better than the old dexamethasone test.
Aldosterone excess causes high blood pressure and low potassium. You only test for this if you have those two things. If you do, check plasma aldosterone and renin levels. If aldosterone is high and renin is low, you have primary hyperaldosteronism-and that’s a reason for surgery, even if the tumor is small.
When Is Surgery Necessary?
Not every adrenal lump needs to come out. But here’s when it does:- All functional tumors: Whether it’s making adrenaline, cortisol, or aldosterone-remove it. Medication can help manage symptoms, but surgery is the only cure.
- All malignant tumors: Adrenocortical carcinoma or metastatic cancer? Surgery is the first step, if possible. Even if it’s spread, removing the primary tumor can help control symptoms and slow progression.
- Tumors larger than 4 cm: Size matters. Tumors under 4 cm have less than a 1% chance of being cancer. Between 4 and 6 cm? Risk jumps to 5-10%. Over 6 cm? Risk hits 25%. So most doctors recommend removal for anything bigger than 4 cm-even if it’s not making hormones.
- Rapid growth: If the tumor grows more than 1 cm in a year, or its volume doubles in under a year, treat it like cancer until proven otherwise.
- Suspicious imaging: Irregular shape, uneven texture, invasion into nearby organs-these are signs of malignancy. Don’t wait.
For benign, non-functioning tumors under 4 cm with normal hormone tests? No surgery. No follow-up needed. Just move on with your life.
What Happens Before Surgery?
If surgery is needed, preparation is critical.For pheochromocytoma: You need alpha-blockers like phenoxybenzamine for at least 7-14 days before surgery. This prevents your blood pressure from spiking during the operation. Beta-blockers may be added later-but only after alpha-blockade. Never start beta-blockers first; that can cause a dangerous blood pressure crash.
For cortisol-secreting tumors: You may need hydrocortisone replacement after surgery because your body has stopped making its own cortisol. Your adrenal gland on the other side may be “asleep” from years of being suppressed. You’ll need steroids for weeks or months until it wakes up.
For aldosterone-secreting tumors: Potassium levels often drop before surgery. You’ll need supplements and medications like spironolactone to stabilize them before the operation.
Who Should You See?
This isn’t a one-doctor job. You need a team.Endocrinologists handle the hormone tests. Radiologists interpret the scans. Surgeons perform the removal. The best outcomes happen when all three work together at a specialized center. Studies show 92% of patients treated at dedicated adrenal centers report high satisfaction. At general hospitals? Only 68% are happy with their care.
Here’s the problem: Only 45% of community hospitals can run plasma metanephrine tests right away. And only 37 U.S. hospitals are officially designated as Comprehensive Adrenal Centers. If you’re diagnosed with an adrenal incidentaloma, ask your doctor: “Can you refer me to a center that sees these regularly?”
What About Tiny Lumps-Under 1 cm?
Some guidelines say anything under 1 cm doesn’t count as an incidentaloma. Others, like the European Society, say 1 cm is the cutoff. In practice, most doctors won’t test or scan something smaller unless you have strong symptoms. But if you’re over 70 and have a 7 mm nodule on a scan? It’s worth a conversation with an endocrinologist.The Hidden Cost-Anxiety and Misinformation
Many patients wait weeks for test results. Some feel like they’re living with a ticking time bomb. A 2022 survey of 142 patients found 78% felt intense anxiety during the evaluation period. That’s real. And it’s not just in their heads.Online forums like Reddit’s r/adrenalfatigue are full of people misinterpreting their scans, thinking every lump is cancer. That’s not true. But the fear is real. That’s why clear communication matters. Your doctor should explain: “This looks like a benign adenoma. No action needed.” Or: “We need to check your cortisol. Here’s what we’ll do next.”
What’s New in 2025?
The field is changing fast. In 2023, researchers started using urinary steroid metabolomics to detect cortisol overproduction. It’s more accurate than the dexamethasone test and doesn’t require you to take a pill. The Endocrine Society is updating its 2020 guidelines in 2025, with new data showing surgery improves blood sugar and blood pressure in patients with cortisol levels above 5.0 μg/dL after the test.Also, more hospitals are adopting laparoscopic adrenalectomy-minimally invasive surgery with small incisions, faster recovery, and less pain. Most adrenal surgeries today are done this way.
Bottom Line
An adrenal incidentaloma isn’t a diagnosis. It’s a starting point. Most are harmless. But some can kill you if ignored. The key is systematic testing: scan first, then hormones, then size. If it’s big, making hormones, or looks suspicious-act. If it’s small, quiet, and looks clean-walk away. No need to panic. No need for surgery. Just know the facts.And if you’re unsure? Get a second opinion from an adrenal specialist. Don’t let fear or confusion delay the right care-or send you down the wrong path.
