Surveillance of ground glass nodules—when is enough, enough?

Lee et al. provide important information about the long-term behavior of ground glass nodules (GGNs) (1). They carried out a retrospective review of 208 GGNs, detected during routine health check-up CT scans (1–3 mm slice thickness), that were stable for 5 years (78% pure GGNs) (1). Growth was defined as an increase in the largest total dimension of ≥2 mm (others have shown high inter- and intra-observer variability for changes of <2 mm) or the development of a new solid component (presumably visible on mediastinal windows although not explicitly stated).