Pulmonary Nodules.

Pulmonary nodules are classified as solid or subsolid, with subsolid nodules further classified as part-solid or pure ground-glass. Management strategies differ according to the type of nodule. A comparison of current and previous imaging studies, when available, is essential to assess the risk of the nodule being malignant. Solid nodules that have been stable for 2 years are considered to be benign, whereas subsolid nodules require a longer period of stability to be considered benign. Prediction models to stratify the risk of the nodule being malignant can be used to guide the management of solid nodules. Computed tomographic (CT) surveillance is indicated for low-risk nodules; positron-emission tomography-CT, biopsy, or both for intermediate-risk nodules; and surgical resection for selected high-risk nodules. Subsolid nodules are often slower growing than solid nodules but are associated with a higher risk of being malignant, especially if a solid component develops or progressively enlarges. Biopsy methods include transthoracic needle biopsy and navigational bronchoscopy. Optimal overall management balances timely diagnosis in persons who have cancer with the avoidance of unnecessary invasive procedures in persons who have benign disease.