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What Are Lung Nodules

A Look at the Spots on Your Lung

Pulmonary nodules, or lung nodules, are common, and are usually benign or non-cancerous. Here’s what you need to know about these spots.

What Are Lung Nodules?


Lung nodules are small masses of tissue in the lung that appear as round, white spots on a chest X-ray or computed tomography (CT) scan. Because they rarely have symptoms, they are usually found incidentally in 1 of every 500 chest X-rays taken for other, unrelated ailments, like a respiratory illness.

Most nodules are smaller than 10 mm, or the size of a cherry. Larger lung nodules, or nodules located near an airway, may have symptoms such as a chronic cough, blood-tinged mucus and saliva, shortness of breath, fever or wheezing.

“Nodules identified on chest X-ray typically require additional evaluation (follow-up or other testing) to determine what they represent,” says Eric M. Hart, MD, a thoracic imaging radiologist at Northwestern Memorial Hospital.

“In our part of the world, very small (less than 6 mm) nodules are commonly identified incidentally on chest CT scans for reasons like chest pain or shortness of breath, or to evaluate for pulmonary embolism,” says Dr. Hart. “The significant majority are benign, although in certain instances they may require follow-up to prove that.”

What Causes Lung Nodules?

The most common causes of lung nodules are tissue that has become inflamed from infection or benign lung tumors. Causes of lung nodules can include:

  • Bacterial infections, such as tuberculosis and pneumonia
  • Fungal infections
  • Rheumatoid arthritis
  • Sarcoidosis
  • Imaging and Diagnosis

    Imaging, like an X-ray or a CT scan, can determine the size, shape and location of your lung nodules. This can help your physician determine the cause and, as a result, the treatment needed.

    Though most lung nodules are not cancerous, it’s important to detect them early. Northwestern Medicine offers a low-dose CT lung cancer screening program specifically for individuals at high risk of lung cancer. To determine your eligibility for the program, your physician will discuss your history, including your smoking history and age.

    A positron emission tomography (PET) scan provides detailed metabolic images that can help fine-tune a diagnosis of cancer. For probable benign lung nodules, your provider may suggest CT scans to monitor the growth over time as a precaution. However, a biopsy may be needed to determine what’s causing the lung nodule from occurring.

    What’s Next?

    Although it can be nerve-wrecking to learn you have lung nodules, they’re quite common and generally do not indicate lung cancer. Your physician will work with you to monitor your condition regularly. Because smoking increases your risk for lung cancer and other health issues, if you smoke, consider quitting.

    Lung Nodule Specialists