The Beth Israel Lung Nodule Center characterizes lung nodules according to specific and accepted medical guidelines.
A lung nodule is an abnormal spot or shadow on an imaging test—typically an X-ray or CT scan—that measures approximately 1.5 cm in diameter or less. Any lung spot that is larger than this is considered a lung mass, and is more likely to be malignant (cancerous) in nature.
Lung nodules are quite common. About 150,000 lung nodules are spotted in X-rays or CT scans in people in the United States every year. The majority of these nodules—about 60 percent—are benign (non-cancerous).
If more than one lung nodule is seen, the chances of a malignant condition increase. However, even multiple lung nodules—on one side or on both the right and left sides—can be benign.