Fleischner criteria
Read Your Scan Editorial Team·Last updated
Written from published radiology references and reviewed for plain language. Not written or signed by a physician, and not a diagnosis. How we write these pages →
In plain language
The published guidance radiologists follow for how to handle a lung nodule found by accident: whether to ignore it, when to re-scan, and for how long. The recommendation depends on the nodule's size and type and on whether you smoke, which is why two people with similar nodules can get different advice.
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Where you'll see this
The impression of a chest CT that mentions a pulmonary nodule.
Your report may word it “Fleischner Society guidelines” or “Fleischner recommendations”. These mean the same thing.
Questions worth asking your doctor
- What category did I get, and what does that category normally lead to?
- What is the recommended next step for this category — waiting, another scan, or a biopsy?
- Who decides the timing, and what should I do if my symptoms change before then?
How often does this turn up?
The Fleischner criteria are referenced on a great many chest CT reports, because incidental lung nodules are extremely common — CT is sensitive enough that small nodules turn up constantly on scans done for something else entirely. The criteria are a set of follow-up recommendations, published by an international society, that answer one question: given this nodule, when should it be looked at again?
Does it mean something is wrong?
The criteria are not a risk score and they say nothing about any individual nodule being cancer. They combine the nodule’s size, whether it is solid or partly solid, whether there is one or several, and whether the person is at higher or lower risk — mainly smoking history — and produce an interval. Their whole design assumes most nodules are benign, which is why the commonest recommendation is to wait and re-image rather than to investigate. They explicitly do not apply to people under 35, to those with known cancer, or to nodules found in an organised screening programme, where Lung-RADS is used instead.
What to do with it
For very small nodules in low-risk people, the recommendation is often no follow-up at all. Otherwise a repeat CT at a defined interval — commonly somewhere between six and twelve months — with further intervals if it stays unchanged. Stability over a couple of years is generally taken as reassurance and the follow-up stops. Growth is what changes the plan, which is why the interval matters more than the nodule’s existence.
Frequently asked questions
- Do the Fleischner criteria tell me if my nodule is cancer?
- No. They are a schedule for when to re-image, built on the assumption that most incidental nodules are benign. They answer the question of when to look again, not the question of what it is.
- Why do I need a follow-up CT if the nodule is probably benign?
- Because time is the most reliable test available. A nodule that has not changed over the recommended interval is very likely benign, and demonstrating that non-invasively is preferable to biopsying something that almost certainly did not need it.
- When do the criteria not apply?
- They are not intended for people under 35, for anyone with a known cancer, or for nodules found in an organised lung screening programme — that last group is handled with Lung-RADS instead. A radiologist chooses the framework that fits the context.
Standard scoring systems
Where this word comes up
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