Incidental Pulmonary Nodules: Differential Diagnosis and Clinical Management

According to data from the USA, the incidence of incidentally discovered pulmonary nodules is 5.8 per 100 000 person- years for women and 5.2 per 100 000 person-years for men. Their management as recommended in the pertinent guidelines can substantially improve clinical outcomes. More than 95% of all pulmonary nodules revealed by computerized tomography (CT) are benign, but many cases are not managed in conformity with the guidelines. In this article, we summarize the appropriate clinical approach and provide an overview of the pertinent diagnostic studies and when they should be performed.

This review is based on relevant publications retrieved by a selective search in PubMed. The authors examined Englishlanguage recommendations issued since 2010 for the management of pulmonary nodules, supplemented by comments from the German lung cancer guideline.

In general, the risk that an incidentally discovered pulmonary nodule is malignant is low but rises markedly with increasing size and the presence of risk factors. When such a nodule is detected, the further recommendation, depending on size, is either for follow-up examinations with chest CT or else for an extended evaluation with positron emission tomography-CT and biopsy for histology. The diagnostic evaluation should include consideration of any earlier imaging studies that may be available as an indication of possible growth over time. Single nodules measuring less than 6 mm, in patients with few or no risk factors, do not require any follow-up. Lung cancer is diagnosed in just under 10% of patients with a nodule measuring more than 8 mm.

The recommendations of the guidelines for the management of incidentally discovered pulmonary nodules are intended to prevent both overand undertreatment. If a tumor is suspected, further care should be provided by an interdisciplinary team.