The histopathology of BRAF-V600E-mutated lung adenocarcinoma.

BRAF mutations in lung adenocarcinoma are much less common than the more frequently reported and mutually exclusive mutations of KRAS and EGFR genes, and the clinical and histologic phenotype of BRAF adenocarcinomas has not been described. We analyzed 222 adenocarcinomas of lung lacking KRAS and EGFR mutations and identified 10 adenocarcinomas with BRAF-V600E mutation. All BRAF-V600E mutations were heterozygous. There was a slight female predilection (6:4) in these elderly patients (average age 67 y) who were found to have a greater than expected incidence of intralobar satellite nodules and N2 node involvement. The adenocarcinomas were largely of mixed type with a high incidence of papillary (80%) and lepidic growth (50%). Adenocarcinomas with this clinicopathologic phenotype may be worthwhile investigating for BRAF-V600E mutation as more genetically oriented drug therapies emerge.