What’s a Pulmonary Nodule?
Key takeaways:
Pulmonary nodules are a common finding on imaging studies of the lungs, such as an X-ray or CT scan. The nodule is a small area of lung tissue that appears more dense than the surrounding tissue.
Providers pay attention to pulmonary nodules because they can be a sign of cancer. But more often, they are harmless and just areas of scarring or inflammation in the lung tissue.
If you have a pulmonary nodule, your provider will assess your risk for lung cancer and recommend follow-up testing if needed.
A pulmonary nodule, or lung nodule, is an area in the lungs that is denser than the surrounding lung tissue. It is like a small ball of inflammation or scar tissue in the lungs.
Pulmonary nodules are commonly seen on radiology tests such as X-rays or CT scans of the chest. Medical professionals usually refer to them as incidental findings. This means that they showed up on the test, but have no relevance to the reason the test was ordered.
Lung nodules can cause anxiety, because small and early cancers can first appear as pulmonary nodules on lung films. Radiologists (the doctors that interpret imaging studies) make note of them, so the person can get screened for cancer if needed.
The good news is that most pulmonary nodules aren’t actually cancer. Learn more about what can cause pulmonary nodules, and what to do if you have one.
How common are pulmonary nodules?
Pulmonary nodules are common and become even more common as people get older. In fact, about 1 in 7 seven CT scans of the chest will show a pulmonary nodule. So if you have a test that shows one, you can rest assured this is not an unusual finding.
Are pulmonary nodules a sign of cancer?
Pulmonary nodules can be a sign of early cancer. That’s why they get some attention from medical providers. However, only about 1 in 20 end up being from lung cancer or are a sign of spread from a different cancer.
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But even though the risk is low that they’re cancer, all pulmonary nodules should be screened for possible cancer.
What else can cause pulmonary nodules?
There are a lot of other conditions — other than cancer — that can lead to pulmonary nodules. Some of these include:
Scar tissue, which can develop after infections in the lungs or from irritants in the air.
Atelectasis, which is when a part of the lung collapses because it isn’t inflated with air. This is temporary, and usually the result of someone not taking deep breaths. It is not an illness, but it can look similar to a nodule in the lungs.
Lymph nodes, which are part of the immune system and can swell when fighting an infection.
Sarcoidosis, a condition in which small pockets of inflamed tissue develop in various places in the body. If they develop in the lungs, they can look like a pulmonary nodule.
Vasculitis, which is when blood vessels in the body get inflamed. This can occur for a number of reasons, including autoimmune disease.
Should I worry about pulmonary nodules?
All pulmonary nodules should be taken seriously until cancer is ruled out. Sometimes, this can be done based on your risk of cancer and the characteristics of the pulmonary nodule.
When you see your provider about a pulmonary nodule, you’ll first figure out your risk for cancer. This depends on several factors, such as:
Your age: The older you are, the higher your risk of cancer. While there is no exact age cutoff, people older than 35 may be at a higher risk of cancer.
Smoking: If you smoke, or smoked for a long period of time, you are at a higher risk of cancer.
A personal history of any type of cancer: A pulmonary nodule could be recurrent cancer or spread of cancer from another place in the body.
The pulmonary nodule’s characteristics can also give clues as to whether or not they are potentially cancerous. Some features your provider will look for include:
Size: Nodules that are less than 6 mm in size are less likely to be cancer. Larger nodules — or ones that are growing over time — have a greater chance of being cancer.
Appearance: A nodule that is a smooth ball is less likely to be from cancer. Nodules that are irregular in shape or have hazy borders are more concerning.
Number: A single nodule may not be as likely to be cancer as multiple different nodules.
If you are at higher risk for cancer, or the nodule has concerning features, your provider may recommend more testing.
What types of tests do I need for a pulmonary nodule?
You and your provider will use all the above information to determine what type of testing you might need. Possible testing includes:
Repeat CT scans: This is usually an option for people who are at a slightly higher risk of cancer. Getting a CT scan every 3 to 6 months can track the size and shape of the nodule over time. If the nodule doesn’t grow for 2 years, it’s likely not cancer.
A positron emission tomography (PET) scan: This test measures the metabolic activity of tissues in the body, or how much energy the cells are using. Cancer cells often use a lot more energy than normal tissue, so they tend to light up on a PET scan.
A biopsy: This is a procedure in which a provider collects a small piece of the nodule to look at under a microscope. If you are at high risk of cancer, or other studies suggest possible cancer, the next step is usually a biopsy.
The bottom line
If you have been told you have a pulmonary nodule, it’s normal to feel some anxiety or fear about cancer. This is why providers pay attention to them. But most pulmonary nodules are not cancer, and there are many other conditions that can cause them.
Your provider will help you determine the right follow-up plan based on your specific situation and risk. Further testing may not even be necessary. But even if it turns out to be cancer, catching a pulmonary nodule may lead to an early diagnosis and easier treatment course.
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References
American Cancer Society. (n.d.). Lung nodules.
American Thoracic Society. (2020). What is a lung nodule?. American Journal of Respiratory and Critical Care Medicine.
Bueno, J., et al. (2018). Updated Fleischner Society guidelines for managing incidental pulmonary nodules: Common questions and challenging scenarios. Radiographics.
Gould, M. K., et al. (2013). Evaluation of individuals with pulmonary nodules: When is it lung cancer? Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines. Chest.
McWilliams, A., et al. (2013). Probability of cancer in pulmonary nodules detected on first screening CT. The New England Journal of Medicine.
Wyker, A., et al. (2021). Solitary pulmonary nodule. StatPearls.
