Comparative analysis of respiratory bronchiolitis-associated interstitial lung disease and desquamative interstitial pneumonia

Abstract

OBJECTIVE: To investigate the clinicopathologic characteristics of respiratory bronchiolitis-associated interstitial lung disease (RBILD) and its relationship to desquamative interstitial pneumonia (DIP). METHODS: The clinical and pathological data of one patient with RBILD confirmed by video-assisted thoracoscopic lung biopsy were reviewed retrospectively, and compared with one patient with DIP. RESULTS: Both patients were 57 year old male, and they had a history of cigarette smoking for 24 and 30 years respectively. The clinical manifestations were cough and sputum production, breathlessness with exertion, and crackles on chest examination. Lung function test showed a mild abnormality with mixed obstructive-restrictive and restrictive pattern respectively. The chest radiograph showed scattered small nodules and patchy densities. High resolution computer tomography showed scattered interstitial infiltrates and reticular changes in the middle and lower lung fields, but patchy ground-glass attenuation was found only in DIP. The pathological examination showed the presence of clusters of pigmented macrophages within the lumens of respiratory bronchioles, alveolar ducts and peribronchiolar alveolar spaces, with patchy submucosal and peribronchiolar infiltration of lymphocytes and histiocytes. Mild peribronchiolar fibrosis was found in RBILD. Compared with RBILD, the lesions of DIP were more severe and widespread. Both the patients responded favorably to glucocorticoids. They were followed for more than three years. CONCLUSION: RBILD could be confused with DIP in clinical manifestations, but can be separated by open lung biopsy. Considering their similarities, these two lesions may be regarded as a same disease entity.