Purpose To assess the characteristics of fibrotic-focilike lung adenocarcinoma on 18 F-fluorodeoxyglucose PET/ computed tomography ( 18 F-FDG PET/CT) and highresolution computed tomography (HRCT). Material and methodsThis was a retrospective study with 20 cases in the fibrotic-foci-like lung adenocarcinoma group; the control group was old fibrotic-foci of the lung with 20 cases. The following 18 F-FDG PET/CT and HRCT features were evaluated: the maximum standardized uptake value (SUVmax); the tumor-to-background ratios of SUVmax (TBRmax); the long-to-short diameter ratio (L/S); anatomic location; location type; internal characteristics; marginal characteristics and surrounding structures. In the fibrotic-foci-like lung adenocarcinoma group, a comparison of 18 F-FDG uptake between the metastatic group (n = 10) and the non-metastatic group (n = 10) was performed. Finally, the comparison of diagnostic accuracy for fibrotic-foci-like lung adenocarcinoma between 18 F-FDG PET/CT and HRCT was performed. ResultsThe SUVmax [2.