Radiologists describe these spots by size in millimeters, density and edge shape, and those details — not the word nodule alone — drive what happens next.
A pulmonary nodule is a small round or oval spot on your lung seen on imaging, defined mainly by its size (American Cancer Society). Major health organizations describe these as a very common incidental finding on adult chest imaging, with the large majority turning out to be benign (Duke Health; American Thoracic Society). A nodule on a report is a description of what the scan shows — it is not a diagnosis on its own.
What your follow-up looks like depends on the nodule's size in millimeters, whether it is solid or ground-glass, and your own risk factors. Bring the printed radiology report to your next appointment rather than relying on memory of the number.
What This Finding Is
A pulmonary nodule is a small abnormal area in the lung, defined by its size, that shows up on a CT scan of the chest or abdomen (American Cancer Society). On the images it usually looks like a round or oval spot against the dark, air-filled lung (MedlinePlus). Radiologists measure it in millimeters, note whether it is solid, part-solid or pure ground-glass (hazy rather than dense), and describe its edges and any calcium inside.
The tissue involved is lung tissue itself, or sometimes a small lymph node or scar sitting within it. Nodules rarely cause symptoms and are most often found on a scan done for some other reason (MedlinePlus; Cleveland Clinic).
As a general pattern reported by major health organizations: most incidentally detected pulmonary nodules turn out to be benign, although most are still classed as indeterminate when first found (American College of Radiology, 2023), and more than half of solitary pulmonary nodules are noncancerous (MedlinePlus). That describes groups of patients, not a prediction about you. One scan finding, on its own, is a measurement and a description — not a diagnosis.
Size, Features, and What They Suggest
Size cutoffs below are the typical ones used in widely cited guidance. Different systems — Fleischner Society criteria for incidental nodules versus Lung-RADS for screening scans — use somewhat different thresholds and editions, so your own report may apply a different one.
| Feature or size range | What it often suggests | Typical follow-up |
|---|
| Solid nodule smaller than 6 mm | Very low likelihood of malignancy (RSNA / Fleischner Society, 2017); lowest-concern Lung-RADS category at baseline (American College of Radiology) | No routine follow-up imaging recommended for indeterminate nodules under 6 mm (American College of Radiology, 2023) |
| Solitary solid nodule 6 mm to 8 mm | Indeterminate; intermediate Lung-RADS category (American College of Radiology) | Initial CT at 6 to 12 months in low-risk patients; one follow-up exam often suffices (RSNA / Fleischner Society, 2017) |
| Solid nodule larger than 8 mm | More likely to be evaluated further rather than just watched | Shorter-interval CT, additional imaging or tissue sampling, as your report and doctor advise |
| Pure ground-glass nodule | Hazy, non-solid; followed over longer periods | Initial follow-up CT at 6 months, especially with risk factors such as larger size (RSNA / Fleischner Society, 2017) |
| Dense or central calcification, or visible fat | Patterns radiologists often read as benign | Often no further imaging; the radiologist states this in the report |
| Stability on serial scans | Solid nodules 6 mm or larger can be safely followed over a 5-year period, with growth typically seen after an average of 3 to 4 years (RSNA / Fleischner Society, 2017) | Surveillance until your doctor says it can stop |
| Whatever interval your report states | Your radiologist weighed your images, prior scans and risk factors | Follow the specific recommendation in your own report — it overrides the general ranges above |
Frequently asked questions
Does a nodule on my CT mean I have lung cancer?
No — a nodule is a described finding, not a diagnosis. Major health organizations report that the large majority of incidentally found pulmonary nodules are benign, most commonly scars from past infection (Duke Health; MedlinePlus). Your doctor weighs size, features, prior scans and your risk factors together before drawing any conclusion.
Why was I told no follow-up scan is needed?
For incidental indeterminate nodules smaller than 6 mm on chest CT, no routine follow-up imaging is recommended because the likelihood of malignancy is low (American College of Radiology, 2023; RSNA / Fleischner Society, 2017). That advice assumes low clinical risk. If you smoke, have a cancer history or have new symptoms, tell your doctor, since that can change the plan.
What symptoms mean I should call before my scheduled follow-up?
Patients with a pulmonary nodule finding are advised to go to the emergency room or call 911 for chest pain, difficulty breathing, or coughing up blood (Cleveland Clinic). Call your doctor's office sooner than planned for a new cough that will not settle, fevers, night sweats or unexplained weight loss. If you feel well and nothing has changed, it is reasonable to keep the interval your report states.
How long will I be followed?
It varies with size and type. Solid nodules 6 mm or larger can be followed safely over a 5-year period, with growth typically identified after an average of 3 to 4 years when it occurs (RSNA / Fleischner Society, 2017). Ground-glass nodules are often watched on a different schedule. Ask your doctor what the end point of your own surveillance plan is.
Should I expect to feel something from the nodule itself?
A solitary pulmonary nodule rarely causes symptoms and is usually found on a scan done for another reason (MedlinePlus). Feeling fine therefore does not tell you what the nodule is, and new symptoms do not automatically mean it has changed. Report any new breathing symptoms to your doctor rather than interpreting them yourself.
