Most lung nodules are noncancerous (benign). However, some lung nodules may be cancerous — either early-stage lung cancer or metastatic cancer that has spread to the lungs from another site in the body.
Lung nodules — small masses of tissue in the lung — are quite common. They appear as round, white shadows on a chest X-ray or computerized tomography (CT) scan. They're usually about .2 inch (5 millimeters) to 1 inch (25 mm) in size. A larger lung nodule, such as one that's 25 mm or larger, is more likely to be cancerous than is a smaller lung nodule.
The most helpful thing your doctor can do is compare your current chest X-ray or CT scan with a previous one. If the nodule on earlier images hasn't changed in size, shape or appearance, it's probably noncancerous. Causes of noncancerous lung nodules include infections, such as histoplasmosis or tuberculosis, a small collection of normal cells (hamartoma), lung cysts, and vascular abnormalities. Noncancerous lung nodules usually require no treatment. However, your doctor will probably monitor the nodule for changes using periodic imaging tests.
If a lung nodule is new or has changed in size, shape or appearance, your doctor may recommend further testing — such as a CT scan, positron emission tomography (PET) scan, bronchoscopy or tissue biopsy — to determine if it is cancerous.
A CT scan is usually the first test if it's suspected that a nodule is malignant. If there is no evidence that the possible cancer has spread, then surgical removal may be recommended. If results of the CT scan are indeterminate, then the decision may be made to observe with follow-up imaging or a biopsy. If you have multiple lung nodules (two or more), especially if not in just one lung, your doctor will work with you to develop a treatment plan that's specific to your case.