Fig. 3

a–d CT images of lung adenocarcinoma. a CT image shows a nodule (7.0 × 5.0 mm) with heterogeneous density and blurred tumor–lung interface (red arrowheads) located in the subpleural zone of the right middle lobe. b One year and a half later, it grew a little (8.0 × 6.0 mm) but its density significantly increased. c Two years and a half later, its size (8.0 × 8.0 mm) slightly increased but margins became clearer than before. Lobulation and pleural indentation (red arrow) are obvious. d Histopathologic analysis of the resected nodule revealed adenocarcinoma without significant invasion