Diagnostic accuracy of cytology in the evaluation of lung lesions

Abstract

Introduction: Bronchoalveolar lavage (BAL) and bronchial brushing (BB) are routinely used cytological techniques for evaluating lung lesions. With the rising incidence of lung cancer, cytology has assumed a central role in the diagnostic workup of pulmonary lesions. This study aimed to evaluate the diagnostic accuracy of BAL, BB, and their combined use in the assessment of lung lesions, using histopathology as the gold standard.

Method: This prospective study was conducted in the Department of Pathology at Patan Academy of Health Sciences, Nepal, from February 2025 to January 2026. A total of 98 cases with paired BAL, BB, and lung biopsy specimens were included. Diagnostic performance parameters, including sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy, were calculated for BAL, BB, and combined cytology.

Result: The study population consisted predominantly of males (69.38%), with a mean age of 63.3 years. Squamous cell carcinoma was the most common malignant diagnosis. Sensitivity was highest for combined cytology (62.50%), followed by BB (57.14%) and BAL (36.73%). Specificity was high for all modalities. Combined cytology demonstrated the highest diagnostic accuracy (78.57%), followed by BB (77.55%) and BAL (67.35%). Concordance between cytology and histopathology for malignant lesions was 63.41%.

Conclusion: Lung cytology demonstrates high specificity but limited sensitivity. Consequently, negative results—especially with BAL—should be interpreted cautiously and correlated with clinical, radiological, and histopathological findings. Cytological evaluation of lung lesions alone is insufficient to exclude malignancy.