A solitary pulmonary nodule is a round or oval spot (lesion) in the lungs that is seen with a chest x-ray or CT scan.

Causes

More than half of all solitary pulmonary are noncancerous (benign). Benign nodules have many causes, including old scars and infections.

Infectious granulomas are the cause of most benign lesions.

You have a greater risk for developing a solitary pulmonary nodule if you have:

• Tuberculosis or been exposed to TB
• Infectious lung diseases caused by fungus, such as:
  • Histoplasmosis
  • Coccidioidomycosis
  • Cryptococcosis
  • Aspergillosis

However, the above conditions makes it more likely that the solitary pulmonary nodule is noncancerous.

Young age, history of not smoking, calcium in the lesion, and small lesion size are factors associated with a noncancerous diagnosis.

Lung cancer is the most common cause of cancerous (malignant) pulmonary nodules.

Symptoms

There are usually no symptoms.

Exams and Tests

A solitary pulmonary nodule is usually found on a chest x-ray. If x-rays repeated over time show the nodule size has remain unchanged for 2 years, it is generally considered benign.

A chest CT scan is often done to look at a solitary pulmonary nodule in more detail.

Other tests used to examine a solitary pulmonary nodule may include:

• PET scan
• Percutaneous needle biopsy
• Single-photon emission CT (SPECT) scan
• Skin tests to rule out infectious causes
• Lung biopsy

Treatment

Ask your doctor about the risks of a biopsy versus monitoring the size of the nodule with regular x-rays.

Reasons for a biopsy or removing the nodule may include:

• Smoking
• The nodule size has grown compared to earlier x-rays
• A CT scan suggests the lesion is malignant (cancerous)

Outlook (Prognosis)

The outlook is generally good if the nodule is benign. If the nodule does not grow larger over a 2-year period, under most circumstances nothing more need be done. On occasion, the appearance of the nodule on CT scan may warrant continued follow-up.

When to Contact a Medical Professional

A solitary pulmonary nodule is usually found by your health care professional when a chest x-ray is performed for some other reason.