A lung nodule is a small, round growth in the lung that shows up on a chest CT or X-ray — smaller than 3 cm by definition.
Most lung nodules are benign — old infections, scar tissue, harmless growths — but a fraction represent early lung cancer, and the size of the nodule largely determines the risk. The challenge is figuring out which need to be biopsied, which need to be watched, and which can be ignored.
Published Fleischner 2017 tiers: ≤6 mm <1%, 6–8 mm 0.5–2%, 8–10 mm 1–4%, 10–20 mm 4–24%, >20 mm 12–53%.
A lung nodule is a small, round growth in the lung that shows up on a chest CT or X-ray. By definition, it's smaller than 3 cm. Most lung nodules are benign — old infections, scar tissue, harmless growths — but a fraction represent early lung cancer, and the size of the nodule largely determines the risk. Lung nodules are common. More than 1.5 million Americans are found to have a lung nodule each year — often incidentally during a CT scan ordered for another reason.
Most lung nodules are silent — they cause no symptoms and are found by accident. If a nodule is growing or large enough to compress structures, it may cause cough, blood in sputum, chest pain, or shortness of breath.
Diagnosis means determining the likelihood that a nodule is malignant, which determines whether to biopsy or follow with imaging. We consider size (under 6 mm = <1% malignancy; 8 mm+ needs attention), density (solid / part-solid / ground-glass), shape (smooth and round usually benign; spiculated suspicious), location, risk factors, and growth on serial imaging. Risk calculators like the Brock Model estimate the probability of malignancy. For higher-risk nodules: PET-CT, biopsy (CT-guided or bronchoscopic), or surgical resection.
Low-probability nodules: serial CT scans per Fleischner Society guidelines. Most resolve or stay stable. Intermediate-probability: PET-CT, biopsy if needed. High-probability: biopsy or direct surgical resection. Confirmed malignancy: refer to thoracic oncology for staging and treatment. AI-assisted analysis (such as Optellum's Virtual Nodule Clinic) can further refine the probability of malignancy for higher-risk patients.
This page is general medical information, not personalized medical advice. If you have questions about your specific health, talk with your Nimbus clinician.
