clinical features that suggest whether SPN is more likely to be malignant and whether it is more likely to be due to lung cancer or a pulmonary metastasis
Older patient age (>35 years old), history of prior malignancy, presence of symptoms and signs of malignancy such as hemoptysis, and history of tobacco use all increase the likelihood that an SPN is malignant rather than benign. In patients with a history of extrapulmonary malignancy, lung cancer tends to be a more frequent cause of SPN than pulmonary metastasis or a benign lesion. However, this can vary depending on the type of extrapulmonary malignancy. For example, a solitary metastasis is a more common cause of SPN than lung cancer in patients with melanoma, sarcoma, and testicular cancer. Multiplicity of pulmonary nodules also favors metastases over lung cancer. Finally, primary lung cancer occurs more commonly in the upper lung fields, whereas pulmonary metastases occur more commonly in the lower lung fields. There are no imaging criteria, however, that can definitively distinguish a solitary pulmonary metastasis from a primary lung cancer.
