Comparison of Conventional Smear and Liquid-based Cytology Preparation in Diagnosis of Lung Cancer by Bronchial Wash and Transbronchial Needle Aspiration

INTRODUCTION: Liquid-based cytology (LBC), initially developed for screening gynecologic specimens, is now being used in nongynecologic aspiration and exfoliative specimens. In this study, the diagnostic yield and utility of thin-prep (TP) was compared with conventional preparations to ascertain its utility in improving the diagnosis of respiratory lesions. MATERIALS AND METHODS: Bronchial washings (BW) and transbronchial needle aspirates (TBNA) (bronchoscopy/endobronchial ultrasound-guided) from 70 consecutive patients of mediastinal masses and endo/peribronchial growths were included. The diagnostic yields of both conventional smears and thin-prep were compared. Immunocytochemistry (ICC) was performed on direct/cytospin smears of TBNA/BW and TP slides when the tumor could not be subtyped by morphology. Histopathologic correlation was done. RESULTS: Although well-preserved morphological features and cleaner background in TP allowed accurate diagnosis of malignancies, diagnostic yield was comparable to conventional preparations. Immunocytochemistry was successfully employed on TP smears which helped in accurate subtyping of the tumors. Few shortcomings of TP smears were uneven distribution of cells, thick cell clusters, and inadequate cellularity. CONCLUSION: Liquid-based TP preparation is an effective diagnostic tool for respiratory tract cytology, however, results are comparable to conventional smears.