Progressive changes in non-neoplastic ground-glass nodules on follow-up computed tomography (CT).

Background: Non-neoplastic ground-glass nodules (GGNs) generally decrease in size or density during follow-up; however, some exhibit the opposite effect (and show progressive changes), which can lead to unnecessary resection. This study sought to determine the progressive changes in non-neoplastic GGNs using follow-up computed tomography (CT). Methods: This cross-sectional study included 70 patients diagnosed with pathologically confirmed non-neoplastic GGNs from January 2017 to March 2023. Of the patients, 35 showed progressive changes and 35 showed no significant changes. The initial and preoperative chest CT images were reviewed to evaluate their changes. The progressive changes in the GGNs were classified into the following five types: type I: increasing density; type II: increasing size; type III: increasing density and solid component; type IV: increasing size and density/solid component; and type V: increasing size, density, and solid component. The T-test, Pearson chi-square test, Wilkinson sign test and Mann-Whitney U-test were used for the data analysis. A two-sided P value <0.05 was considered statistically significant. Results: Among the 35 GGNs with progressive changes, type II (14, 40.0%) was the most common, followed by types IV (9, 25.7%), I (5, 14.3%), V (5, 14.3%), and III (2, 5.3%). The number of lesions that changed in <6, ≥6 and <12, ≥12 and ≤24, >24 months was 22 (62.9%), 4 (11.4%), 5 (14.3%), and 4 (11.4%), respectively. Among the 28 GGNs with an increasing volume, the number of lesions with a volume doubling time (VDT) of <344 and >441 days was 20 (71.4%) and 8 (28.6%), respectively. Except for these progressive changes, the other features did not exhibit significant changes, especially the ill-defined boundary (74.3% Conclusions: GGNs with progressive changes are more likely to be non-neoplastic if the changes occur in a short period or the lesions maintain an ill-defined boundary.