Lung Nodule
A lung nodule is a small, round or oval spot in the lung that appears on imaging, usually measuring less than 3 centimeters in diameter. Lung nodules are very common and are often discovered incidentally during CT scans or X-rays performed for other reasons. Most nodules are benign, especially in people who do not smoke, but some require follow-up to ensure they do not grow or develop concerning features.
What is it?
A lung nodule is a small area of abnormal tissue within the lung. Nodules can vary in appearance—they may be solid, partially solid, or ground-glass (a hazy type of nodule seen on CT). They commonly result from healed infections, inflammation, scarring, or benign growths. Less commonly, a lung nodule can represent an early lung cancer, especially if it grows over time or has high-risk features.
Radiologists assess several characteristics to determine how concerning a nodule may be, including its size, shape, edges, density, and growth pattern. Comparison with older imaging is important, as stability over two years often indicates a benign cause. Guidelines based on size and appearance help determine when follow-up scans are needed.
Important to Know
Most lung nodules—especially those smaller than 6 mm—are benign and do not require aggressive follow-up. However, certain factors increase the chance that a nodule could be cancerous, including smoking history, older age, irregular or spiculated borders, rapid growth, and nodules larger than 8 mm. Nodules that change in size or appearance during follow-up require further evaluation.
Follow-up CT scans are typically recommended at set intervals depending on the nodule’s size and type. Some nodules may also require a PET/CT scan or biopsy to determine their nature. Red flag symptoms include persistent cough, coughing up blood, unexplained weight loss, or new shortness of breath—especially in people with risk factors for lung cancer. Early detection and monitoring help ensure concerning nodules are identified and treated promptly.