What Causes Lung Nodules?

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According to the Seattle Cancer Care Alliance, lung, or pulmonary, nodules have numerous causes, including fungal or bacterial infection, sarcoidosis, lymphoma, lung cancer and cancers metastasized from other organs. The Mount Sinai Beth Israel Lung Nodule Center adds that medical conditions that cause swelling, thickening and scarring of pulmonary tissues, such as healed pulmonary infarcts and chronic bronchopneumonias, can also cause lung nodules.

Pulmonary nodules can grow to become pulmonary masses if their diameter is three centimeters or more. The Seattle Cancer Care Alliance points out that less than 10 percent of lung nodules are lung cancer. According to the University of Rochester Medical Center, benign lung nodules usually require no treatment, while cancerous nodules require surgery. Thoracotomy or thorocoscopic surgery is recommended for those with malignant lung nodules.

To diagnose or detect lung nodules, and to try to find their causes, doctors perform PET scans, CT-guided needle biopsies and bronchoscopy. The Seattle Cancer Care Alliance suggests using CT scans to follow pulmonary nodules because many of them are less than one centimeter in diameter and can be early signs of lung cancer. These small nodules are generally followed for two years. Additionally, the SCCA states that if their size does not change, then it is concluded that the nodules are not precancerous.