Metastatic disease to the lungs and pleura: an overview

The lungs are a common site for metastatic spread of malignancy. Approximately 20%-54% of patients with extrathoracic malignancy have pulmonary metastases at autopsy. The most common primary neoplasms with pulmonary metastases at autopsy include breast, colon, kidney, uterus, and head and neck. Less common primary malignancies including choriocarcinoma, osteosarcoma, testicular tumors, melanoma, and thyroid carcinoma also metastasize to the lungs. The detection of pulmonary metastases, as with other distant metastases, indicates a poor prognosis and directly affects treatment planning. For example, in a large retrospective study of patients with melanoma, median survival was only 7.3 months after development of pulmonary metastases. Evaluation is primarily performed with chest radiography and computerized tomography (CT), although other modalities such as fluorodeoxyglucose-positron emission tomography (FDG-PET) may also play a role. Pulmonary metastases can have a wide spectrum of appearances on imaging, reflecting the route of spread as well as the local behavior of the neoplastic cells.