A. Pure ground glass opacity (GGO) nodule with poorly defined margins – adenocarcinoma in situ
B. Subsolid nodule with spiculated margins – invasive adenocarcinoma
C. GGO containing small solid components with poorly defined margins – adenocarcinoma in situ
INV = invasive
Pre-INV = pre-invasive adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA)