A solitary pulmonary nodule (SPN) is a single round or oval lesion in the lungs. Typically, an SPN causes no symptoms. It is usually found during a chest X-ray or CT scan. This condition is also known as a solitary coin lesion.
Your doctor may perform a biopsy to find out if the nodule is cancerous or noncancerous. About half of all SPNs are noncancerous, or benign. These SPNs are the result of scarring or bacterial infections. As long as the benign nodule remains the same size, it will generally not need to be treated.
You are at a higher risk to develop a cancerous SPN if you smoke or have been exposed to carcinogens, cancer-causing agents. You may also develop an SPN if you have cancer in another part of your body and it metastasizes (spreads) to your lungs.
According to an article in the journal Applied Radiology, there are about 130,000 cases of SPNs each year in the United States (AR, 2004).
About half of all SPN’s are noncancerous and may have one of several causes, such as infection and scarring. Most benign lesions develop as a reaction to a previous infection. This is called a granuloma.
Some common bacterial infections that can cause SPNs include:
Lung cancer is the most common cause of malignant (cancerous) SPNs. These lesions are the first indication of lung cancer in about 20 to 30 percent of patients. About 10 to 30 percent of cancerous SPNs occur when a cancer spreads to the lungs from another part of the body.
There are usually no symptoms of an SPN. Your doctor will usually discover an SPN during an X-ray or CT scan of the chest. These tests are usually ordered to diagnose another condition.
After your doctor discovers the nodule, he or she must determine if it is cancerous. First, your doctor will conduct a complete physical exam and take your medical history. He or she will ask if you are a smoker or have been exposed to agents that cause cancer.
The SPN is likely to be noncancerous if it is less than 3 centimeters wide and has a smooth border with an even appearance. It is also less likely to be cancerous if you are a young nonsmoker.
In this case, your doctor may want to take a "wait and see" approach. He or she will order follow-up X-rays or CT scans to compare with your starting or baseline information and images. Your doctor may decide that a biopsy is not necessary if the nodule does not change in two years.
A biopsy may be recommended if:
- the nodule is larger than 3 centimeters across
- the nodule has changed in size or appearance
- you have other symptoms of lung cancer
- you are a smoker
A biopsy removes a tissue sample from the SPN, which is then sent to a laboratory for examination under a microscope. Your doctor can perform a biopsy in one of the following ways:
- lung needle biopsy: a needle is inserted through the chest wall
- bronchoscopy: a scope is passed through the mouth into the lungs
- mediastinoscopy: a lighted instrument is inserted into the area between the lungs, called the mediastinum
Your doctor may also order a simple skin test to rule out various bacterial infections, such as tuberculosis.
Based on your X-ray or CT images and your physical examination, your doctor will decide whether you should have a biopsy. If not, he or she may recommend careful follow-up testing.
If the nodule is noncancerous and does not change over the course of two years, no further treatment is needed. If a biopsy indicates that you have cancer, you should consult an oncologist, a doctor who specializes in cancer, as soon as possible. A quick diagnosis and immediate treatment can be crucial in lung cancer cases.