TP53 and small cell lung carcinoma: However, it is plausible that SCLC and adenocarcinoma components both arose from the same origin, because in our case each histologic portion shared the same mutations in EGFR and TP53. In previously reported cases that experienced acquired resistance to EGFR-TKI via SCLC transformation3, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, all SCLC components also harboured the same activating EGFR mutation as the adenocarcinoma component.