Role of Bronchoalveolar Lavage in Interstitial Lung Disease Diagnosis: A Cytological Perspective.

Abstract

Objectives: Interstitial lung diseases (ILDs) are a heterogeneous group of pulmonary disorders requiring a multidisciplinary diagnostic approach. Bronchoalveolar lavage (BAL) is a minimally invasive procedure that provides cellular insights into lung pathology. This study evaluates the role of BAL cytology in ILD cases.

Materials and methods: This observational study was conducted at a tertiary care health care center, from April 2023 to June 2024. A total of 100 ILD patients were enrolled, out of which 31 patients who required multidisciplinary diagnosis (MDD) for a final diagnosis of ILD were included. BAL fluid was processed using cytocentrifugation and stained with Giemsa and Papanicolaou stains, and differential cell count patterns (cellular analysis) were assessed in 400 cells. In cases of sarcoidosis, endobronchial biopsy was performed in five cases, and endobronchial ultrasound-guided transbronchial needle aspiration was performed in nine cases. The MDD approach incorporated clinical features, high-resolution computed tomography, biochemical, microbiological, biopsy, and cytology findings.

Results: The mean age of patients was 41.2 ± 12.2 years, with a female predominance (74.2%). The distribution of ILD subtypes included sarcoidosis (45.2%), connective tissue disease-associated interstitial lung disease (CTD-ILD) (25.8%) idiopathic nonspecific interstitial pneumonia (6.5%), and hypersensitivity pneumonitis (HP) (22.6%). BAL cellular analysis showed lymphocytosis in sarcoidosis (41.8%) and chronic HP (56.7%) with neutrophilia (mean value >20%). The CTD-ILD cellular pattern is similar to that of sarcoidosis. BAL findings corroborated with the final diagnoses in cases with multiple differentials.

Conclusion: BAL cellular analysis is a valuable tool in the MDD approach to ILD diagnosis. The presence of lymphocytosis in BAL commensurates with sarcoidosis and chronic HP diagnosis. The presence of concurrent neutrophilia in such cases may not necessarily be considered in lines of an infective etiology or acute exacerbation.