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Hypersensitivity Pneumonitis, Transbronchial Biopsy, Bronchoalveolar Lavage
Introduction: The diagnosis of chronic hypersensitivity pneumonitis (cHP) is based on clinical data, tomographic patterns and, in some cases, on pathologic findings. The role of bronchoscopy is uncertain, especially in the fibrotic form. Aim: To analyze the yield of transbronchial biopsy (TBBx) in patients with cHP according to tomographic findings and to evaluate the importance of bronchoalveolar lavage (BAL) in the diagnostic approach. Methods: A retrospective study of patients with cHP who underwent TBBx in São Paulo, Brazil. The TBBx findings were classified as characteristic (granulomas and/or multinucleated giant cells, associated or not with peribronchiolar infiltration of lymphocytes and plasma cells and bronchiolocentric distribution) and supportive (data indicative of small airway injury: peribronchiolar metaplasia, organizing pneumonia, and intra-alveolar foamy macrophages). Results: One hundred nine patients were included. The presence of characteristic findings of HP were seen in 15 cases (13.8%) and supportive findings in 33 (30.2%), with a total yield of 44%. The pathologic characteristic findings were more common in cases without fibrosis on high-resolution computed tomography (HRCT) (24.2% vs. 9.2%, p= 0.036), whereas the presence of supportive findings was more common in fibrotic HP (38.1% vs. 12.1%, p= 0.007). Fifty-two patients had differential cytology on BAL. Lymphocytosis (> 20%) was present in 51.9% of the patients. There was no difference in the median of the lymphocytes according to tomographic findings indicative or not of fibrosis on HRCT. Conclusion: TBBx has a role to the diagnosis of HP and in association with BAL should be used as the initial option in the investigation of the disease.