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 historically 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 h Objective Diffuse panbronchiolitis, a distinct clinical entity of unknown etiology, has been reported originally and Young in Japanese and rarely in non-Japanese populations. Only 2 cases have Difficult 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 historically 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 h ad elevated cold h