Figure 2a:

Dramatic radiographic response to erlotinib in a 55-year-old man with stage IV adenocarcinoma of the lung harboring exon 19 deletion of EGFR. (a) Contrast-enhanced CT scan of the chest before therapy demonstrates an irregular mass in the right middle lobe (arrow), with multiple metastatic nodules in both lungs. (b) Follow-up CT scan after 2 months of erlotinib therapy show near-complete resolution of the dominant mass with very faint residual opacities in the right middle lobe (arrow), representing a marked response to therapy. Bilateral metastatic nodules also decreased in size and number.