Incidentaloma on Radiology Reports: What It Means

ByA. Mendelson, MD
Please read the disclaimer

When people undergo imaging such as CT, MRI, or ultrasound, radiologists sometimes discover a finding that is unexpected and not contributing to the patients symptoms. These are called incidentalomas—findings that were not the reason for the scan . Understanding what the word means and how doctors approach it is helpful when a report mentions an incidental finding.

What Is an Incidentaloma?

An incidentaloma is a growth or abnormality that shows up on imaging by chance. The patient usually had the scan for another reason—for example, abdominal pain, lung infection, or trauma—and the radiologist notices an unrelated lesion.

The most common sites where incidentalomas are found include:

  • Adrenal glands (adrenal incidentaloma)

  • Thyroid gland (thyroid nodules)

  • Liver and kidneys (cysts or masses)

  • Lungs (small nodules)

  • Brain (benign cysts or small vascular changes)

Why Do Incidentalomas Happen More Often Now?

With advanced CT and MRI technology, scans capture very fine detail. This allows radiologists to detect even tiny changes in organs and tissues. While this improves diagnosis of disease, it also increases the chances of seeing unrelated findings.

Decades ago, many of these growths went unnoticed. Now, even a scan done for kidney stones might reveal a small adrenal nodule that has nothing to do with the patient’s symptoms.

Are Incidentalomas Dangerous?

Most incidentalomas are benign, meaning they are not cancer and do not cause harm. For example, many people have small cysts in the kidney or liver that never cause problems.

However, a small percentage can represent something more serious, such as:

  • Cancer or precancerous lesions

  • Hormone-producing tumors (in the adrenal glands)

  • Infections or inflammatory conditions

Because of this, radiologists report incidentalomas carefully and recommend follow-up when needed.

How Do Radiologists Report Incidentalomas?

When an incidentaloma is seen, the radiology report will usually describe:

  • Size – Smaller lesions are usually less concerning.

  • Shape and margins – Smooth and well-defined lesions are often benign. Irregular margins may need more attention.

  • Density or signal characteristics – On CT, the Hounsfield units (HU) can suggest if a lesion is fatty, cystic, or solid. On MRI, signal changes help in characterization.

  • Enhancement with contrast – Whether the lesion takes up contrast can help distinguish benign from malignant growths.

Radiologists may include recommendations such as:

  • “No follow-up needed.”

  • “Consider repeat imaging in 6–12 months.”

  • “Suggest further evaluation with MRI or biopsy.”

Common Types of Incidentalomas

1. Adrenal Incidentaloma

Most are benign adenomas, but doctors often check hormone levels and sometimes order further imaging.

2. Thyroid Incidentaloma

These appear on CT, MRI, or ultrasound of the neck. Most thyroid nodules are benign, but larger or suspicious ones may need biopsy.

3. Kidney and Liver Incidentalomas

Simple cysts are very common and harmless. Solid or complex lesions may require additional imaging or follow-up.

4. Lung Incidentaloma (Nodule)

Lung nodules are often discovered on chest CTs done for other reasons. Many are scars or benign granulomas, but some may need surveillance to rule out early cancer.

5. Brain Incidentaloma

Small cysts, vascular malformations, or benign tumors may be seen on brain MRI. Most do not require treatment but are followed depending on size and appearance.

How Doctors Decide What to Do Next

The management of an incidentaloma depends on several factors:

  • Patient age – Some guidelines for follow up depend on patient age

  • Risk factors – Smoking history or family history of cancer

  • Imaging appearance – Radiologists apply criteria from professional guidelines to decide if follow-up is necessary.

  • Change over time – Growth or change in appearance is more concerning than stability.

Often, the safest option is watchful waiting, where repeat imaging is done.

The Emotional Impact of Incidentalomas

Hearing about an incidentaloma can cause stress. Patients may fear the worst, even though most findings are not serious. Radiologists use published guidelines to avoid unnecessary testing and to focus attention only on lesions that may matter.

It’s important to remember that the goal is caution, not alarm. Incidentalomas are common in modern imaging, and most people will have one or more discovered in their lifetime without it ever becoming a health problem.

Conclusion

An incidentaloma is simply an unexpected finding that was not the reason for the test and does not explain the symptoms. While the word may sound worrisome, the majority of these findings are harmless. Radiologists carefully evaluate these lesions to decide whether follow-up is needed. In some cases, incidentalomas may require follow up to make sure they are not something that can cause harm.

References

https://www.acr.org/Clinical-Resources/Clinical-Tools-and-Reference/Incidental-Findings

https://www.radiologyinfo.org/en/info/all-about-your-radiology-report

https://pmc.ncbi.nlm.nih.gov/articles/PMC3200145/

Disclaimer: The content of this website is provided for general informational purposes only and is not intended as, nor should it be considered a substitute for, professional medical advice. Do not use the information on this website for diagnosing or treating any medical or health condition. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider.

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