Presence of EGFR mutation in pathologically non-malignant specimens from computed tomography-guided lung needle biopsies

Activating mutations of the epidermal growth factor receptor (EGFR) gene are characteristic of non-small cell lung cancer (NSCLC). EGFR mutations were previously detected in histologically normal lung tissue around NSCLC tumors. Computed tomography-guided lung needle biopsy (CTNB) is an accurate and useful technique for the diagnosis of lung tumors. However, pathologically non-malignant cases occasionally become apparent following lung tumor resection. In this study, we determined the EGFR mutational status of lung tumors diagnosed as non-malignant in CTNB specimens, but diagnosed as NSCLC following surgical resection. Between 2000 and 2008, 1,109 CTNBs were performed at Okayama University Hospital. Among them, 15 cases were initially diagnosed as non-malignant by CTNB, but diagnosed as NSCLC following surgical resection as a result of a high likelihood of malignancy by clinical findings. Twelve paired DNAs of CTNB and corresponding resected specimens were available to examine the EGFR mutational status using a mutant-enriched PCR assay. EGFR mutations were detected in one out of 12 CTNB specimens and three of the corresponding resected tumors. This case harbored the same EGFR mutation in the CTNB specimen and resected tumor, but not in the distant corresponding non-malignant lung tissue. Our results indicated that the detection of EGFR mutations may therefore aid the diagnosis of NSCLC in pathologically non-malignant CTNB specimens.