What is the size criterion for defining a pulmonary nodule?

A pulmonary nodule is defined as a small, rounded growth in the lung that is typically less than 3 cm in diameter. Nodules larger than 3 cm are classified as masses. This distinction is important because the management and clinical significance of pulmonary nodules differ based on their size. Nodules that are 3 cm or smaller are often monitored for changes over time, while larger growths may prompt a more aggressive investigation due to a higher risk of malignancy. Thus, the correct size criterion for defining a pulmonary nodule is indeed less than 3 cm.