One of the most common referral requests is for evaluation of a pulmonary nodule found on CT scanning of the chest, often times found while looking for other problems. Patients will often present with a very worried look, not really understanding what was found on their CT scan. The first question is often “What is a nodule?” A nodule, by definition, is a small (<3cm), focal, distinct density seen on CT scanning, completely surrounded by lung tissue. These are often found because CT scanning is so common, and is more diagnostic than the routine chest x-rays in the past. Many of the nodules, depending on size, would never have been seen on a routine chest x-ray.
Pulmonary nodules are found in approximately 1.6 million people per year in the U.S., and detected on approximately 30% of CT scans of the chest. More than 50% of patients with a pulmonary nodule have more than one.
The obvious concern with a nodule is the possibility of cancer. How we proceed with the assessment of a nodule depends on the patient’s risk factors, such as a significant smoking history, and the size of the nodule. The probability of malignancy is less than 1% in all nodules smaller that 6mm. For most of the nodules evaluated that are under 1 cm in diameter, follow up CT scanning at 6 or 12-month intervals is the approach most often taken.
Other follow up schedules may apply in some circumstances. Check with your doctor