Incidentaloma: What an Incidental Finding on Imaging Really Means
An incidentaloma is something the radiologist notices on your scan that has nothing to do with why the scan was ordered. Most are benign — but some need follow-up.
Plain-language definition
An incidentaloma is something the radiologist notices on your imaging study that wasn't the reason the study was ordered. The term is a play on the medical suffix -oma (meaning "mass" or "growth"), combined with incidental. It can refer to any incidental finding, but the word is most often used for unexpected small masses or nodules.
Classic examples include:
- A small kidney cyst seen on a lumbar spine MRI ordered for back pain.
- A 5 mm lung nodule seen on a chest CT done after a car accident.
- A small thyroid nodule seen on a neck CT done for sinusitis.
- A tiny adrenal nodule seen on an abdominal CT done for kidney stones.
- A small liver lesion seen on an ultrasound done for gallbladder symptoms.
Modern imaging is so detailed that incidentalomas are common — often present in 20–40% of scans depending on the body part. The vast majority are benign.
Why it matters
Incidentalomas matter because they create three possible problems:
- Real disease can hide as an incidentaloma. A small percentage of incidental nodules turn out to be early cancer or another condition that benefits from treatment.
- Over-investigation. Aggressive work-up of every incidentaloma can lead to unnecessary biopsies, anxiety, cost, and even harm.
- Anxiety and confusion. Patients understandably worry when a scan ordered for one problem reports something unexpected.
To balance these risks, the radiology community has built evidence-based guidelines for nearly every common incidentaloma — kidney, adrenal, pancreatic, lung, liver, thyroid, ovarian, and more. The guidelines tell the radiologist (and your provider) exactly how to characterize the finding, when no follow-up is needed, and when a short-interval follow-up scan or specialist referral is warranted.
When the radiologist writes "follow-up CT in 6 months," they are almost always working from one of these well-established guidelines — see our follow-up imaging explainer.
How incidentalomas show up in a Precise Imaging context
Precise radiologists apply current society guidelines (ACR, Fleischner Society, ACR LI-RADS, ACR TI-RADS, and others) when describing and managing incidentalomas. A typical report will:
- Describe the finding with measurements and any features that affect management (size, density, enhancement, location).
- Categorize it where applicable (e.g. Lung-RADS, LI-RADS, TI-RADS, Bosniak for renal cysts).
- Recommend a specific next step in plain language — "no further imaging needed," "follow-up CT in 12 months," "dedicated MRI for further characterization," etc.
We deliberately avoid the term "tumor" for indeterminate or clearly benign findings to reduce unnecessary worry. The radiologist's recommendation is just that — a recommendation. Your ordering provider remains the decision-maker for your individual care.
Disclaimer
This explainer is general patient education and not medical advice. The clinical meaning of any incidental finding on your scan depends on its size, appearance, location, and your medical context. Always discuss imaging results with your ordering provider before deciding on next steps.
Frequently asked questions
Are incidentalomas usually cancer?
No. The great majority are benign — cysts, calcifications, hamartomas, focal fatty changes, and other normal variations. A small percentage are malignant, which is why guideline-based follow-up matters.
Will I be told about every incidentaloma?
Every clinically meaningful incidental finding is described in your report. Trivial findings (a tiny kidney cyst clearly benign by appearance, for example) may be mentioned for completeness and may not require any follow-up.
What should I do if my report mentions a follow-up scan?
Talk to your ordering provider. They'll review the radiologist's recommendation in the context of your medical history and decide whether to schedule the follow-up, refer you to a specialist, or take a different path.
Can I get a second opinion?
Yes. You can request a second opinion on any imaging study — either by asking your provider to refer you or by contacting Precise's records team directly to have the study reviewed by a sub-specialist.
Why are incidentalomas so common today?
Modern CT and MRI scanners image at sub-millimeter resolution, finding things that older imaging technology would have missed. Incidentalomas are the price of that increased sensitivity — and they're why guideline-driven follow-up has become so important.