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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 of 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 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:
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.
Gould MK, Fletcher J, Iannettoni MD, et al. Evaluation of patients with pulmonary nodules: when is it lung cancer? ACCP evidence-based clinical practice guidelines (2nd edition). Chest. 2007;132:108S-130S.
Hansell DM, Lynch DA, McAdams HP, Bankler A. Imaging of Diseases of the Chest. 5th ed. Philadelphia, Pa: Elsevier Mosby; 2009: chap 3.
Ost DE, Gould MK. Decision making in patients with pulmonary nodules. Am J Respir Crit Care Med. 2012;185:363–372.
Padley S, MacDonald SLS. Pulmonary neoplasms.In: Adam A, Dixon AK, Grainger RG, et al., eds. Grainger & Allison’s Diagnostic Radiology: A Textbook of Medical Imaging. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 18.