Concordance of Bronchoalveolar Lavage Fluid Cytology with Respect to Histological Diagnosis of Cancer: A Cross-sectional Study

Introduction: Bronchoalveolar Lavage (BAL) is a minimally invasive procedure that allows for the sampling of distal airways and the alveolar environment to diagnose infectious and non infectious respiratory tract diseases. It is a safe and reliable method considered for diagnosis. Aim: To evaluate the concordance of BAL cytology with the histopathology report of biopsied cases concerning cancer diagnosis. Materials and Methods: The study was a cross-sectional observational study conducted in the Department of Respiratory Medicine at King George’s Medical University, Lucknow, Uttar Pradesh, India, which is a tertiary care teaching hospital in northern India. Reported BAL cytology cases for one year, from September 2022 to September 2023, were retrieved from records and consecutive histology was followed for cytohistological correlation. The sensitivity, specificity, Negative Predictive Value (NPV) and Positive Predictive Value (PPV) of BAL cytology were calculated with reference to the identification of malignancy. Histological diagnosis was considered the gold standard and the specificity, sensitivity, positive predictive value and NPV of BAL were calculated. Results: The BAL was performed in 261 cases with a mean age of 56.79 years. The adequacy of BAL cytology was 88.12% (230/261). Of the 261 cases, eight were positive for epithelial malignancies, three were suspicious for malignancies, 219 were reported as negative for malignant cells and 31 cases were deemed inadequate. A biopsy was performed in 56 out of 261 cases (21.45%) and 32 of these cases were found to have epithelial malignancy. A total of 13 cases were reported negative for malignancy, of which 12 were in concordance with BAL results. Three cases were reported as suspicious for malignancy and three were diagnosed as non epithelial malignancies on biopsy, which were deemed inadequate on cytology. Based on the interpretation of the data, the specificity of BAL cytology with respect to histology was 100%, with a PPV of 100%; however, the sensitivity was 14.28% and the NPV was 28.57. Conclusion: The present study results clearly show that BAL cytology is a specific test for malignant diagnosis in lung lesions, in addition to its role in inflammatory conditions. However, due to its low sensitivity, it may not serve as a good screening method. BAL fluid cytology primarily samples the lower respiratory tract, which may not always be affected by malignancy. The low sensitivity may also be attributed to procedural and interpretation limitations. It can serve as a complement to bronchial brushings and histology for the diagnosis of lung cancers.