More than half of all solitary pulmonary nodules are noncancerous (benign). Benign nodules have many causes, including old scars and infections.
Infectious granulomas (reactions to a past infection) cause most benign lesions. Common infections that increase the risk for developing a solitary pulmonary nodule include:
Lung cancer is the most common cause of cancerous (malignant) pulmonary nodules.
The nodule itself rarely causes symptoms.
A solitary pulmonary nodule is most often found on a chest x-ray or a chest CT scan, which are often done for other symptoms or reasons.
Your doctor must decide whether the nodule in your lung is probably benign (not cancer). This is more likely if:
Your doctor may then choose to just watch the nodule on x-rays.
Your doctor may choose to biopsy the nodule to rule out cancer if:
Skin tests to rule out tuberculosis and other infections may also be done.
Ask your doctor about the risks of having a biopsy versus monitoring the size of the nodule with regular x-rays or CT scans. Treatment may be based on the results of the biopsy or other tests.
The outlook is usually good if the nodule is benign. If the nodule does not grow larger over a 2-year period, often nothing more needs to be done.
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Wahidi MM, Govert JA, Goudar RK, et al. Evidence for the treatment of patients with pulmonary nodules: when is it lung cancer?: ACCP evidence-based clinical practice guidelines (2nd edition). Chest. 2007;132:94S-107S.
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Ettinger DS. Lung cancer and other pulmonary neoplasms. In: Goldman L, Ausiello D, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 197.