01 · Basics
Pulmonary Nodule
A pulmonary nodule is a small, rounded opacity in the lung — typically ≤ 30 mm in diameter. Most are found incidentally on CT scans ordered for unrelated reasons.
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≤ 30 mm in diameter
Larger opacities are classified as "masses" and managed with a different protocol.
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~96% are benign
Most are caused by old infections, scar tissue, calcified granulomas, or inflammation.
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Three key features
Radiologists assess size, density, and margin to determine follow-up interval and urgency.
Educational use only · Not a medical device
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