Fig. 1

Computed tomography (CT) findings of primary lung cancer (LC) and solitary lung metastasis (LM). a Lung window image of contrast-enhanced chest CT scan showing a solitary nodule (white arrows) with sub-solid density, spiculated smooth margin, and presence of an air bronchogram (black arrow) in the right upper lobe. The nodule was histopathologically confirmed to be LC. b Lung window image of contrast-enhanced chest CT scan showing a solitary nodule (white arrows) with solid density and lobulated margin in the right lower lobe. The nodule was histopathologically confirmed to be LM