Hi there. Secondary lung tumors manifest as discrete nodules, usually multiple, interstitial infiltrate or endobronchial lesions with or without distal atelectiasis and charcterisitc round appearance on xray chest. Any cancer has the ability to spread to lungs most common being bladder, colon, breast and prostate cancer. You will need a PET scan to confirm and differentiate from pneumoconiosis since malignant cells have higher rate of glucose metabolism. Thus, the principle of PET scan is intracellular accumulation of FDG snd preferential accumulation of glucose in malignant cells, leads to visualization of malignancy on PET scan. It is the diagnostic and staging tool in cancer, assesses malignant potential in a pulmonary nodule if it is solid and more than 1 cm in dia. management would depend on the diagnosis. Primaries would need to be searched if these are secondaries. Hope this helps. Take care.