Lung nodules, also called pulmonary nodules, are small round growths on the lung that are smaller than three centimeters in diameter. These nodules are easily detected on an X-ray, appearing as a white shadow. Since about 40 percent of all detected nodules are cancerous, the first step is to determine if it is cancerous or benign (non-cancerous). Benign lung nodules have different characteristics than their cancerous counterparts.
A benign lung nodule is usually very small--less than three centimeters in diameters. A growth larger than this is considered a mass and is evaluated using different clinical tests. Benign lung nodules have a smooth surface and even color throughout. In contrast, a cancerous lung nodule will be irregularly shaped with a rough surface and a speckled appearance.
The most pronounced characteristic of a benign lung nodule is that it grows or changes very little and usually not at all. A cancerous growth, however, grows very rapidly. Cancerous lung nodules will usually double in size at least every four months, if not sooner.
Since benign lung nodules are small and do not grow, they rarely cause noticeable symptoms. In fact, most benign lung nodules are detected when a chest X-ray or computed tomography (CT) scan are performed for an unrelated reason. In the rare case a patient does experience symptoms due to the benign lung nodule, the symptoms are similar to that of a chest cold or a mild case of the flu.
Most benign lung nodules are caused by scar tissue left after an infection. Patients who have had tuberculosis are more likely to have a benign lung nodule. Also, those who have had a fungal infection such as histoplasmosis may develop a benign lung nodule. A benign lung nodule can also be congenital, meaning present at birth.
Because benign lung nodules do not cause symptoms or pose any further health threats, there is no need for treatment. Your doctor may want to monitor the nodule over time using radiographic tests such as X-rays or CT scans just to be sure that there is no change in size or shape. If change is ever detected, then you may need to undergo further testing to be sure that your benign lung nodule is in fact benign, and not cancerous.