Diffuse Panbronchiolitis

Abstract

Diffuse panbronchiolitis (DPB), a unique chronic obstructive pulmonary disease of unknown pathogenesis, is characterized clinically by progressive airflow limitation and respiratory tract infection and pathologically by chronic inflammation principally affecting respiratory bronchioles. Although the disease has been noted almost exclusively in Japan, there are several case reports of DPB occurring in North America and Europe. Patients present with a history of chronic cough, copious amounts of purulent sputum, and dyspnea on exertion and often give a long history of sinusitis. Physical examination reveals wheezes and crackles, and pulmonary function testing shows a mixed obstructive and restrictive pattern. Chest roentgenogram and high-resolution CT demonstrate diffuse, ill-defined small nodular shadows that are distributed in a centrilobular fashion and often connect to small, branching linear structures. Histologic confirmation is of primary importance in the diagnosis of DPB. The most characteristic findings are chronic infiltration and accumulation of foam cells in the walls of respiratory bronchioles extending out to the lung parenchyma. Prognosis of DPB was poor, but it has substantially improved after the introduction of low-dose, long-term erythromycin therapy. The beneficial effect of macrolide antibiotics may be due to an antiinflammatory rather than antibacterial action, but the precise mechanism remains to be determined.