What Causes Nodules in the Lungs?

Reviewed on 4/30/2021

A lung nodule is a small round to oval mass of tissue in the lung.
A lung nodule is a small round to oval mass of tissue in the lung.

A lung nodule is a small round to oval mass of tissue in the lung. Nodules in the lung can be either cancerous (malignant) or noncancerous (benign). Most nodules less than 2 cm in diameter are benign. Benign lung nodules can have different causes. Many are caused due to inflammation in the lungs that may occur as a consequence of an infection or other diseases. The nodules may be the result of scar tissue formation related to prior inflammation. Some of the causes include

Should I worry that I have a nodule?

Most nodules aren’t cancer. However, for a small number of individuals, the nodule may turn out to be early cancer. A physician identifies and confirms the lung nodules as cancer by

  • Checking how it looks on a computed tomography (CT) scan.
  • Observing whether it grows over time. A nodule increasing in size over time may indicate lung cancer.
  • Taking a biopsy of the nodule to confirm the cause. Most people with a nodule do not require a biopsy.

How is the cause of pulmonary nodules diagnosed?

If the physician suspects a pulmonary nodule, they will perform a physical examination and order tests to confirm the diagnosis. Some of the tests include

Depending on the features and size of the lung nodule on the CT scan, the physicians may also recommend

  • Observing and repeating X-ray tests if the nodule is probably benign.
  • Further imaging, such as a repeat CT scan of your chest or a PET scan.
  • Taking a biopsy of the nodule via
    • bronchoscopy (if the nodule is near one of your airways)
    • a needle biopsy (if the nodule is located near the outside of your lungs)
    • lung surgery (video-assisted thoracoscopic surgery) if the nodule seems to be cancerous


Lung cancer is a disease in which lung cells grow abnormally in an uncontrolled way. See Answer

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