Evaluation of the solitary pulmonary nodule.

Solitary pulmonary nodules are common radiologic findings, typically discovered incidentally through chest radiography or computed tomography of the neck, chest, and abdomen. Primary care physicians must decide how to pursue an evaluation of a nodule once it has been identified. The differential diagnosis for pulmonary nodules includes benign and malignant causes. Diameter of 8 mm or more, "ground-glass" density, irregular borders, and doubling time between one month and one year suggest malignancy. The American College of Chest Physicians recently released guidelines for the evaluation of solitary pulmonary nodules, based primarily on nodule size and patient risk factors for cancer. Algorithms for the evaluation of lesions smaller than 8 mm and those 8 mm or greater recommend different imaging follow-up regimens. Fluorodeoxyglucose-positron emission tomography can be used to aid decision making when cancer pretest probability and imaging results are discordant. Any patient with evidence of a nodule with notable growth during follow-up should undergo biopsy for identification. The rationale for closely monitoring an incidentally found pulmonary lesion is that detection and treatment of early lung cancer might lead to decreased morbidity and mortality.