Cytological analysis of bronchoalveolar lavage in patients with interstitial lung diseases and the relation of cytological analysis to fibrosis in high-resolution computed tomography.

OBJECTIVE: To evaluate the value of differential cytology of bronchoalveolar lavage (BAL) in common interstitial lung diseases (ILDs) and its relation with high-resolution computed tomography (HRCT) fibrosis.

STUDY DESIGN: A retrospective analysis of BAL from 91 patients. The total and percentage of cells were collected and analyzed according to published guidelines.

RESULTS: The main diagnoses were connective tissue diseases (n = 24), hypersensitivity pneumonitis (HP) (n = 15), sarcoidosis (n = 12), idiopathic pulmonary fibrosis (IPF) (n = 14), smoking-related interstitial lung diseases (sr-ILDs) (n = 8), aspiration (n = 8), and others (n = 10). The lymphocyte percentages differed among diagnoses (F = 2.85, p = 0.008). A greater number of lymphocytes were found in sarcoidosis (Md = 20%, IQR = 12-45%), HP (Md = 29%, IQR = 13-55%), and organizing pneumonia (Md = 28, IQR = 9-50%). No patient with IPF presented with > 25% lymphocytes in BAL. In 6/15 (40%) of the HP cases, the percentage of lymphocytes was < 25%. A total of 56 participants (62%) displayed HRCT findings that were indicative of fibrosis. In those cases the percentage of lymphocytes was 10.1 (IQR = 6.1-18.0) as compared with 20.2% (IQR = 9.7-37.5) of those 35 cases without fibrosis (p = 0.007). In patients with fibrosis in HRCT, the percentage of neutrophils was 11.3 (IQR = 4.1-21.4) as compared with 3.8 (IQR = 1.4-3.8) in those without fibrosis (p = 0.009).

CONCLUSION: Several patterns in differential cytology are observed in common ILDs. The presence of fibrosis has an impact on these findings.