A Spot on the Lung: What Does It Mean?

Your doctor told you that a chest X-ray has revealed a “spot” on your lung. What does this mean, and what could be the cause of it? While a spot on the lung—also called a lung or pulmonary nodule—may be an early warning sign of lung cancer, it is often not cancerous.

Spot Tests

A chest X-ray is usually the first test your doctor will perform to look for spots or masses on your lungs. This X-ray may be given at an imaging center or hospital. While not all lung cancers will appear on an X-ray, you likely do not have lung cancer if the X-ray looks normal.

If a spot does appear on your X-ray, your doctor will probably want to order more tests to learn more, such as:

Benign Nodules

The appearance of a lung spot on an X-ray is common and typically indicates a benign condition. Lung nodules may be caused by marks or scars left from previous infections, such as:

• Fungal infection like histoplasmosis or coccidioidomycosis;
• Bacterial infection like meningitis or pneumonia;
• Mycobacterial infection like tuberculosis;
• A benign tumor known as a hamartoma.

Size Wise

A lung nodule is a spot which is at least two centimeters in diameter appearing on an X-ray of the lung. Spots that are smaller than one centimeter often cannot be seen on a chest X-ray. And spots that are more than two centimeters are considered a mass, not a nodule.

Smaller nodules are more likely to be benign than larger nodules. If your doctor finds a nodule less than five millimeters (approximately one-fifth of an inch), then it is almost certainly benign. However, according to the Mayo Clinic, nodules that measure over 20 millimeters (around three-quarters of an inch) have a more than 50 percent chance of being cancerous.

Reasons for Concern

Nodules are so common that they are found in about half of all chest X-rays performed. A solitary nodule that appears on a chest X-ray may be an early sign of lung cancer, but only your doctor can determine this for sure.

Factors that influence the likelihood that a solo spot on a lung X-ray indicates cancer include:

• If you’re in your fifties or older, you have a 50 percent chance of a nodule being cancerous. In fact, people under 35 have a less than 1 percent chance of a nodule being cancerous.
• Smokers have an increased risk of lung cancer.
• Family history. Those with a family history of lung cancer are more likely to develop the disease.
• Asbestos exposure. Previous exposure to asbestos is another risk factor for lung cancer.

Monitoring for Changes

Most lung nodules don’t have any symptoms associated with them, so your doctor may want to monitor them. Nodules that grow are more likely to be cancerous. Be prepared for repeat X-rays to observe any changes or growth. Your doctor may recommend continous monitoring for up to two years if size, appearance, or shape of a nodule differs from previous X-rays.

It can be scary to hear that you have a suspicious X-ray. However, keep in mind that a spot on a chest X-ray is common and lung nodules usually indicate a benign condition rather than cancer. Nevertheless, a spot on the lungs can sometimes indicate a problem and your doctor should monitor it closely over time for changes and growth.