A pulmonary nodule, or lung nodule, is defined as a “spot” on a diagnostic image of the lung that is 2 cm in diameter or less. If an abnormality is seen on an x-ray of the lungs that is larger than 2 cm, it is considered a “mass” instead of a nodule. Lung nodules usually need to be at least 1 cm in size before they can be seen on a chest x-ray.
Lung Nodules and Lung Cancer
The risk of a lung nodule being cancerous varies considerably depending on several factors. In people less than 35 years of age, the chance that a lung nodule is cancer is less than 1%, whereas half of lung nodules in people over age 50 are cancerous. Other factors that raise or lower the risk that a lung nodule is cancer include:
- Size – Larger nodules are more likely to be cancerous than smaller nodules.
- Smoking – Current and former smokers are more likely to have cancerous lung nodules than never smokers.
- Occupation – Some occupational exposures raise the likelihood that a lung nodule is cancer.
- Medical history - Having a history of cancer increases the chance that a lung nodule is malignant.
- Shape – Smooth, round nodules are more likely to be benign, whereas irregular nodules are more likely to be cancerous.
- Growth – Cancerous lung nodules tend to grow fairly rapidly with an average doubling time of about 4 months, while benign nodules tend to remain the same size over time.
- Calcification – Lung nodules that are calcified are more likely to be benign.
- Cavitation – Lung nodules where the interior part of the nodule appears darker on x-rays are more likely to be benign.
Types of Lung Nodules
Lung nodules can be either benign (non-cancerous) or malignant (cancer). Lung nodules can be broken down into a few major categories:
- Infections - This includes bacterial infections such as tuberculosis, fungal infections such as histoplasmosis and coccidiomycosis, and parasitic infections such as ascariasis (roundworms).
- Inflammation - Conditions such as rheumatoid arthritis, sarcoidosis, and Wegener’s granulomatosis can cause lung nodules.
- Benign tumors - Benign lung tumors such as hamartomas can show up as a nodule in the lungs on x-ray.
- Malignant tumors – This includes lung cancer, lymphomas, and cancer that has spread to the lungs from other parts of the body, among others.
Causes of Lung Nodules
The most common causes of benign nodules include:
- Granulomas: clumps of inflamed tissue
- Hamartomas: benign lung tumors
Valley Fever is an infection commonly seen in the desert regions of the southwest U.S. This fungal infection starts in the lungs by breathing in fungal particles from the soil. On an X-ray nodules can develop on the lungs which may look like cancer. A biopsy or surgery may be needed to determine if the nodule is the result of Valley Fever.
The most common cause of malignant lung nodules include lung cancer, or cancer from other regions of the body that has spread to the lungs (metastatic cancer).
Lung Nodule Symptoms
Most lung nodules do not have any symptoms and are found “accidentally” when a chest x-ray or computerized tomography (CT scan) is done for some other reason. If symptoms are present, they may include a cough or coughing up blood if the nodule(s) is located near a major airway.
Diagnosis of Lung Nodules
The first thing your doctor will want to do if she sees a lung nodule on your x-ray is to obtain any previous x-rays you have had and compare them. If the nodule or nodules have been present for a long time, further tests may not be needed. If the lung nodule is new or you don’t have any prior x-rays to compare, further workup may include:
- Observation and repeat x-ray studies if the nodule is likely benign
- Further imaging, such as a CT scan of your chest or a PET scan
- Biopsy of the nodule via bronchoscopy (if the nodule is near one of your airways), a needle biopsy (if the nodule is located near the outside of your lungs), or lung surgery (video assisted thoracoscopic surgery (VATS) or thoracotomy)
Treatment of Pulmonary Nodules
The treatment of lung nodules varies widely depending upon the cause, whether they are related to infections, inflammation, cancer, or other conditions. Most benign lung nodules, especially those that are present and haven’t changed over a period of a few years, can be left alone.
What Makes Us Different
At St. Joseph's, pulmonary nodule findings are reviewed by a multidisciplinary team composed of infectious disease, pulmonary, thoracic radiologists, thoracic surgeons, internal medicine, and oncology. The team develops a treatment plan based on the scans reviewed and refers each patient to the appropriate specialist. Referring physicians will be notified of the plan and treatment options for the patient.
Referral to our Pulmonary Nodule Clinic
If you have a lung nodule and would like to be evaluated by our multidisciplinary team of doctors, please call our nurse coordinator at (602) 406-3716 or fax a referral form to (602) 406-3090.
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