An early event of EGFR mutation in pleomorphic carcinoma of the lung.

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) are effective in prolonging progression-free survival time of patients with non-small cell lung carcinoma, typically adenocarcinoma, bearing some active EGFR mutations in their tumors. However, the close relationship between the EGFR mutations and pleomorphic carcinoma of the lung, which is a very rare type of primary lung cancer, has never been elucidated. We present a 60-year-old Japanese woman with pleomorphic carcinoma of the lung that became resistant to cytotoxic chemotherapies including platinum-based chemotherapy, and her general condition seriously deteriorated. Thereafter, treatment with gefitinib was started and resulted in significant tumor shrinkage and a dramatic improvement in her general condition for up to 8.5 months. Analyses of the EGFR mutation in separately microdissected specimens from adenocarcinoma and spindle cell components revealed that both components possessed the L858R point mutation. These findings gave us some insight into the carcinogenesis of pleomorphic carcinoma of the lung in relation to EGFR gene alteration. Testing for EGFR mutation may be important in patients with advanced pleomorphic carcinoma including adenocarcinoma component that is usually chemoresistant.