Cytomorphological features as predictors of epidermal growth factor receptor mutation status in lung adenocarcinoma.

Background: Epidermal growth factor receptor mutation-positive ( EGFR-p ) lung adenocarcinomas are sensitive to tyrosine kinase inhibitors. Although histopathological subtype is an independent predictor of mutation status, there is a paucity of data on the cytomorphological features correlating with the EGFR mutation status. Therefore, the aim of this study was to determine whether certain cytomorphological features correlate with EGFR mutation in lung adenocarcinoma.

Materials and Methods: A retrospective analysis of 48 lung adenocarcinoma cases diagnosed on fine needle aspiration cytology with known EGFR mutation status was conducted. All cytology smears with cellblock sections were reviewed. The cytomorphological features including tumor pattern, stromal features, nuclear and cytoplasmic features, and tumor grade were evaluated. Clinicoradiological features such as age, sex, smoking, tumor size, clinical stage, metastases, and presence of mass, nodule, lymphadenopathy, pleural effusion, and clinical outcome were also assessed.

Results: Of 48 cases, 19 were EGFR-p and 29 were negative. EGFR-p cases showed a positive and significant correlation with flat monolayered sheets and acini, mild nuclear atypia, fine chromatin and smooth nuclear margins and these tumors were well differentiated. EGFR -negative tumors were moderate to poorly differentiated with predominance of solid clusters, moderate to marked nuclear atypia, with irregular nuclear margins and coarse chromatin. Clinically, female sex, nonsmoking status, smaller tumor size, and good clinical outcome correlated with EGFR-p status.

Conclusion: Certain cytomorphological features correlate with and may suggest EGFR mutation status in advanced lung adenocarcinoma in an appropriate clinical context.