GGO and minimally invasive adenocarcinomas: how to deal with?

In this issue of the Journal, Mai et al. report on the development of a model that predicts the malignancy and invasiveness of ground-glass nodules (GGNs) based on CT-scan features (1). Similar to previously reported studies, the proposed model showed random forests could achieve 95% and 83% accuracy to predict malignancy and invasiveness, respectively. GGNs may actually corresponds to multiple histopathological entities from the Word Health Organization, including atypical adenomatous hyperplasia, adenocarcinoma in situ, as well as minimally-invasive adenocarcinoma, defined as a GGN up to 3 cm with up to 5 mm invasion; the later possibly being mucinous and/or non-mucinous (2). From a radiological standpoint, pure GGN have to be distinguished at computed-tomography (CT)-scan, from sub-solid and part solid-solid nodules, that may combine limited to more extensive solid component, that is more frequent in larger lesions, and is significantly associated with invasion (3,4)