[A case of respiratory bronchiolitis-associated interstitial lung disease]

A 37-year-old man was referred to our hospital with a cough. His blood test result and chest radiography findings were normal. High resolution chest computed tomography (HRCT) showed diffuse ground glass attenuation (GGA) with centrilobular distribution in the bilateral upper lung fields. As diagnosis could not be made using transbronchial lung biopsy and bronchoalveolar lavage, video-assisted lung biopsy was performed. The histological findings were a thickening of the alveolar walls with infiltration of lymphocyte-dominant inflammatory cells, and exudation of pigmented macrophages in the air spaces of the respiratory bronchioles and alveolis. We diagnosed his illness as respiratory bronchiolitis-associated interstitial lung disease. Six months after stopping smoking, his symptoms, and the GGA on chest HRCT improved.