摘要Objective Diffuse panbronchiolitis, a distinct clinical entity of unknown etiology, has been reported originally and primarily in Japanese and rarely in non-Japanese populations. Macrolide therapy is effective for this once dismal disease. Diffuse panbronchiolitis complicated with thymoma is uncommon; only 2 cases have been reported to date. The aims of this study were to describe the clinical profiles, assess the response to macrolide therapy, and to discuss the possible pathogenesis of diffuse panbronchiolitis in this setting.Methods The clinical profiles, macrolide therapy response of diffuse panbronchiolitis complicated with encapsulated thymoma in 2 histologically confirmed cases were described and discussed with the 2 cases reported in the literature: one complicated with encapsulated thymoma, another with invasive thymoma.Results Of the 2 cases, both had negative PPD skin testing and abnormal serum levels of various immunoglobulins, 1 had positive anti-nuclear antibody, but none had elevated cold hemagglutinin titers, and both had an excellent response to macrolide therapy. Of the 2 cases reported in the literature, both had negative PPD or tuberculin skin testing, 1 had severe hypogammaglobulinemia, 1 had elevated IgA, 1 had positive anti-DNA, 1 had elevated cold hemagglutinin titers, but both died of respiratory failure in spite of macrolide therapy in 1 case.Conclusions Prognosis for diffuse panbronchiolitis complicated with thymoma may depend on the nature of the thymoma and on the disease course. Macrolide therapy is also effective if administered early in the disease course and if the thymoma is cured. Immunological factors may play an important role in the pathogenesis of diffuse panbronchiolitis in this setting.