Fig. 2. Radiologically, LUAD develops from GGO (ground-glass opacity) to mixed and non-GGO. Pathologically AIS lesions progresses to MIA when invasion occurs. If the invasion exceeds 5 mm, then the MIA will progress to the next step. White arrow indicates pure GGO, and red arrow indicates the solid portion of a GGO nodule, yellow arrow indicates a non-GGO lung nodule.