Lung Cancer: Nodules and Masses

The chapter titled Nodules and Masses discusses these frequent imaging manifestations of primary lung cancer. A lung nodule is a roughly spherical, circumscribed density that measures < 3 cm. A lung mass is larger than 3 cm. Lung cancer may manifest as a solitary pulmonary nodule or mass. Most solitary pulmonary nodules on radiographs are benign, and the majority represent granulomas and intrapulmonary lymph nodes. Larger lung nodules and lung masses are more likely to be malignant. Nodule assessment includes determination of size, morphology, attenuation, metabolic activity, enhancement characteristics and growth. A solid lung nodule that is stable for 2 years is generally presumed benign. Sub-solid (part-solid and ground-glass nodules) often represent indolent lung cancer, and different follow-up and management guidelines apply. Confident diagnosis of benign nodules such as granulomas is important, as these lesions do not require imaging follow-up.