In our study, the pleural effusion pellet of NSCLC patient was positive for EGFR by IHC staining, and the patient was examined to have EGFR L858R mutation and wild-type 790th site by ARMS in clinical laboratory, meanwhile her plasma ctDNAs collected at the same day and were analyzed by NGS. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.