Rebiopsy with Thoracoscopy under Local Anesthesia for the Detection of EGFR T790M Mutation.

A 70-year-old woman underwent right upper lobectomy for adenocarcinoma of the lung (pT1bN2M0 stage IIIA). Five years after the surgery, lymph node recurrence was detected. Gefitinib was administered because epidermal growth factor (EGFR) exon 19 deletion mutation was detected in the previously resected surgical specimen. After a treatment of first-generation EGFR tyrosine kinase inhibitors, an FDG-PET/CT scan demonstrated abnormal FDG uptake in the pleura indicating pleural dissemination. Pleurocentesis revealed tumor cells in the pleural fluid; however, EGFR mutation testing failed due to inadequate tumor cellularity. Thoracoscopy under local anesthesia revealed multiple nodules on the parietal pleura. A biopsy specimen confirmed the diagnosis of lung adenocarcinoma with pleural dissemination and revealed EGFR exon 20-T790M mutation.