Figure 2a:

Images in 63-year-old woman with advanced adenocarcinoma of the lung harboring sensitizing epidermal growth factor receptor (EGFR) L858R mutation who was treated with the EGFR inhibitor erlotinib. (a) Baseline chest CT image shows a large irregular mass in the left upper lobe (_*) with thickening of the peribronchovascular bundle and interlobular septa, representing a primary tumor with regional lymphangitic spread. (b) Follow-up chest CT image obtained after 2 months of erlotinib therapy shows a marked decrease of the mass with residual opacities, representing response to therapy.