KRAS and small cell lung carcinoma: However, a subsequent histopathological second look revealed combined histology (the two cases harboring EGFR mutations), intermediate histology between large cell neuroendocrine carcinoma and SCLC (the cases harboring ATM mutation and MET amplification), a grade 2 neuroendocrine tumor/atypical carcinoid of either pancreatic or pulmonary origin (the case harboring BRCA1 mutation), a suspected hepatobiliary origin (the case harboring KRAS mutation), and a suspected prostatic origin (the case harboring TMPRSS2-ERG fusion).