A lung nodule is a small growth on the lung. To be considered a lung nodule, the growth usually must be smaller than 3 centimetres.
Lung nodules are either considered noncancerous or cancerous. A noncancerous nodule is called benign, and a cancerous lung nodule is referred to as malignant. Growths that are larger than 3 centimetres are usually called lung masses and typically have a higher chance of being cancerous.
Noncancerous lung nodules can have a variety of causes, including:
- Infection: Infections, such as previous tuberculosis, or tuberculosis exposure can cause inflammation. A group of cells called a granuloma may form around the inflamed area in the lung.
- Non-infectious inflammation: Inflammation that is not related to an infection can also develop in the lung.
- Non-cancerous tumours: Non-cancerous growths, such as a fibroma, which is a benign growth of connective tissue, may also develop in the lung.
Although most lung nodules are not cancer, some do turn out to be malignant. Certain risk factors increase the risk for cancer like smoking, older age or have a family history of cancer etc. Larger lung nodules are also more likely to be cancerous.
If your doctor detects a lung nodule on an imaging test, it’s helpful to compare your current imaging scan with a previous one. If the nodule on earlier images hasn’t changed in size, shape or appearance in two years, it’s probably noncancerous.
Noncancerous lung nodules usually require no treatment. In some cases, you may need annual chest imaging to see if a lung nodule grows or changes over time.
If a lung nodule is new or has changed in size, shape or appearance, you may have further testing — such as a CT scan, positron emission tomography (PET) scan, bronchoscopy or tissue biopsy — to determine if it’s cancerous.