Lung is the most common site of metastatic involvement for many malignant tumors. The most frequent abnormalities are solitary or multiple pulmonary nodules (large "cannonball" nodules or diffuse miliary pattern), and lymphangitic carcinomatosis. Pulmonary metastases usually occur in a context of a previously known tumour, but sometimes may reveal a latent tumour. Most patients receive palliative treatment with chemotherapy, or hormone therapy (for metastases of breast cancer, thyroid, endometrial carcinoma or prostatic cancer). Patients may rarely benefit from resection of pulmonary metastases.