Novel use for an EGFR mutation-specific antibody in discriminating lung adenocarcinoma from reactive pneumocyte hyperplasia.

Aims: Pulmonary ground-glass nodules (GGNs) are frequently observed. Histopathologically, their presentation can indicate a wide range of disorders from an inflammatory process to malignancy. An accurate diagnosis based on GGNs can sometimes be challenging on small-sized biopsies. Mutations in the EGFR gene are detected in pulmonary adenocarcinomas (ADCs). Immunohistochemical analysis using antibodies that detect specific EGFR mutations has been shown to correlate with mutational status as determined by molecular methods. We hypothesized that these antibodies could be used to discriminate between ADCs and benign pneumocyte hyperplasias.

Methods And Results: Surgically resected, pre-invasive to invasive lung ADC (n = 32) and reactive pneumocyte hyperplasia (n = 40) tissue samples were probed with antibodies against EGFR mutations, p53, Mouse double minute 2 and 14-3-3 sigma. Of the 32 lung ADC specimens analysed, 12 (38%) were positive using the EGFR mutation-specific antibodies, while no immunoreactivity was observed in reactive pneumocyte hyperplasia specimens. Analyses of receiver operating characteristic curves showed that the highest area under the curve values were associated with the use of EGFR mutation-specific antibodies. In addition, a high concordance rate was observed between surgically resected and corresponding biopsy materials using these antibodies.

Conclusions: EGFR mutation-specific antibodies can be used to discriminate between lung ADC and benign pneumocyte hyperplasia, even in small-sized biopsies.