Indeterminate Nodule on Radiology Reports: What It Means

ByA. Mendelson, MD
Please read the disclaimer

When you read a radiology report, sometimes you may come across the phrase “indeterminate nodule.” This wording can be confusing and even alarming if you are not familiar with medical terminology. In simple terms, an indeterminate nodule is a small spot, lump, or lesion seen on an imaging test—such as a CT scan, MRI, ultrasound, or X-ray—that cannot be clearly labeled as either benign (harmless) or malignant (cancerous) based on that single study.

Radiologists use this phrase when the appearance of the nodule is not specific enough to give a clear answer. Instead of guessing, they document it as indeterminate and usually recommend follow-up imaging, clinical correlation, or sometimes a biopsy for more information.

What Is a Nodule in Imaging?

A nodule is a small abnormal area in an organ or tissue. Nodules can occur in many places, including:

  • Lungs (pulmonary nodules)

  • Thyroid gland (thyroid nodules)

  • Liver (hepatic nodules)

  • Kidneys

  • Lymph nodes

  • Soft tissues

They are often found incidentally when imaging is done for another reason. Most nodules are benign, especially if they are small, but radiologists must carefully evaluate them.

Why “Indeterminate” Matters

When a radiologist calls a nodule indeterminate, it means:

  • The nodule does not have classic benign features.

  • The imaging appearance is not clearly cancerous either.

  • Additional information is needed to know more.

This term is a careful and responsible way of reporting. It avoids overcalling something as cancer while still signaling that follow-up is important.

Common Locations for Indeterminate Nodules

Indeterminate Pulmonary Nodule

On chest CT, small lung nodules are extremely common. Many are due to old infections, scarring, or inflammation. If a nodule cannot be clearly classified, it is labeled indeterminate pulmonary nodule.  There are established guidelines for lung nodule follow up mostly based on size.

Indeterminate Thyroid Nodule

On thyroid ultrasound, nodules are very frequent. Some have benign patterns while others raise more suspicion. If the nodule falls in between, radiologists call it indeterminate. In these cases, further steps such as a fine-needle aspiration biopsy may be recommended.

Indeterminate Liver or Kidney Nodule

In abdominal imaging, lesions in the liver or kidneys are sometimes discovered incidentally. If they do not show the clear features of benign cysts or hemangiomas, they may be labeled indeterminate. Contrast-enhanced MRI or CT can often help clarify the diagnosis.

Imaging Features That Lead to Indeterminate Classification

Radiologists look at several factors when evaluating nodules. An indeterminate label may be used if:

  • The size is too small to characterize reliably.

  • The density or signal on CT or MRI is not specific.

  • The nodule has mixed features, some benign and some suspicious.

  • There is motion or artifact that limits evaluation

  • No prior imaging is available for comparison.

Next Steps After Finding an Indeterminate Nodule

If your report mentions an indeterminate nodule, your doctor will usually recommend one or more of the following:

  • Follow-up imaging to see if the nodule changes in size or appearance.

  • Additional imaging with contrast to better characterize the nodule.

  • Biopsy if the nodule is large, suspicious, or in a high-risk patient.

  • Clinical correlation with symptoms, blood tests, or history.

The approach depends on the organ involved, the size of the nodule, your risk factors, and your overall health.

Risk Factors That Influence Concern

Not all nodules are treated the same way. Doctors weigh the following:

  • Patient age – younger patients are more likely to have benign nodules.

  • Smoking history – increases concern for lung nodules.

  • History of cancer – raises the likelihood that a nodule could be malignant.

  • Symptoms – nodules found in patients with pain, weight loss, or abnormal labs may require closer attention.

Why Comparison With Prior Imaging Is Crucial

One of the most powerful tools radiologists have is comparison with older studies. A nodule that has been stable for many years is much more likely to be benign. If no prior images exist, short-term follow-up is often suggested to establish whether the nodule is stable or changing.

Key Takeaways

  • An indeterminate nodule is a finding on imaging that cannot be clearly labeled benign or malignant.

  • Most indeterminate nodules turn out to be harmless, but they require follow-up to be sure.

  • Location, size, imaging features, and patient history all play a role in determining the next steps.

  • The phrase is meant to be cautious, not necessarily alarming—it reflects the uncertainty that is part of medical imaging.

Conclusion

Hearing that you have an “indeterminate nodule” on a radiology report can sound unsettling. However, in many cases, these nodules are benign and only need monitoring. Radiologists use this term when the imaging features are not definitive, and additional evaluation is needed. The key is not to panic but to follow up as recommended by your doctor. With proper surveillance, most indeterminate nodules can be safely evaluated over time.

References

https://www.cancer.org/cancer/types/lung-cancer/detection-diagnosis-staging/lung-nodules

https://www.radiologyinfo.org/en/info/us-thyroid

https://www.cancer.org/cancer/types/liver-cancer/detection-diagnosis-staging/how-diagnosed.html

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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