Fig. 2

a–c CT images of lung adenocarcinoma. a CT image shows an irregular solid nodule (10 × 15 mm) with heterogeneous density located in the apico-posterior segment of the left upper lobe. b One year later, its size (14 × 16 mm) and density increased; the tumor–lung interface was clearer and spiculation (red arrows) was more obvious than before. c Histopathologic analysis of the resected nodule revealed invasive adenocarcinoma