Background Diffuse panbronchiolitis (DPB) was originally and is still primarily reported in Japan, rarely in other countries. As macrolide therapy is effective for this disease with once dismal prognosis, familiarity with its clinical features is urgently needed, especially for clinicians outside Japan. The objectives of this study were to investigate the clinical features of DPB in a Chinese population and propose diagnostic procedures that will lead to increased awareness of this treatable disease among clinicians, ultimately allowing for more rapid diagnosis.Methods After a literature review, the clinical features of DPB were histopathologically confirmed in a series of 9 cases either by open lung biopsy or video-assisted thoracic surgical biopsy, resulting in the largest series of confirmed DPB cases in a non-Japanese population. Here, the cases are retrospectively described and diagnostic procedures are discussed.Results Persistent cough, sputum, and exertion dyspnea occurred in 89% of patients, a history of or current chronic sinusitis in 78%, centrilobular micronodules appearing on chest CT scans in 100%, coarse crackles in 78%, FEV 1/FVC<70% in 44%, PaO 2<80 mmHg in 56%, and titer of cold hemagglutinin≥1∶64 in 11%. According to its clinical diagnostic criteria, diagnosis was definitive in 44%, suggested in 33%, and excluded in 23% at the time of diagnosis. However, DPB was clinically considered before confirmation in only 22% of patients, with the remaining 78% of cases missed or mistaken for other diseases. Of the 9 cases, 8 received transbronchial biopsies before confirmation of the diagnosis, but all showed non-specific inflammation.Conclusions Although its clinical features may vary with disease course and ethnic populations, most cases of DPB can be diagnosed or suggested according to clinical diagnostic criteria. However, underdiagnosis as a result of unfamiliarity with its clinical features and diagnostic criteria prevails. If difficulty in diagnosis arises, the diagnosis should be based on clinicopathological features and the exclusion of other diseases. Few cases can be confirmed by transbronchial biopsies; in these cases, either an open-lung biopsy or a video-assisted thoracic surgical lung biopsy should be recommended. Background Diffuse panbronchiolitis (DPB) was originally and is still primarily reported in Japan, rarely in other countries. As macrolide therapy is effective for this disease with once dismal prognosis, familiarity with its clinical features is urgently needed, especially for clinicians outside Japan. objectives of this study were to investigate the clinical features of DPB in a Chinese population and suggested diagnostic procedures that will lead to increased awareness of this treatable disease among clinicians, ultimately allow for more rapid diagnosis. Methods After a literature review, the clinical features of DPB were histopathologically confirmed in a series of 9 cases either by open lung biopsy or video-assisted thoracic surgical biopsy, resulting in the largest series of confirmed DPB cases in a non-Japanese population. Here, the cases are retrospectively described and diagnostic procedures are discussed.Results Persistent cough, sputum, and exertion dyspnea occurred i n 89% of patients, a history of or current chronic sinusitis in 78%, centrilobular micronodules appearing on chest CT scans in 100%, coarse crackles in 78%, FEV 1 / FVC <70% in 44%, PaO 2 <80 mmHg in to 56%, and titer of cold hemagglutinin ≧ 1: 64 in 11%. According to its clinical diagnostic criteria, diagnosis was definitive in 44%, suggested in 33%, and excluded in 23% at the time of diagnosis. However, DPB was clinically considered before confirmation in only 22% of patients, with the remaining 78% of cases missed or mistaken for other diseases. Of the 9 cases, 8 received transbronchial biopsies before confirmation of the diagnosis, but all showed non-specific inflammation .Conclusions However, under clinical features may vary with disease course and ethnic populations, most cases of DPB can be diagnosed or suggested according to clinical diagnostic criteria. However, underdiagnosis as a result of unfamiliarity with its clinical features and diagnostic criteria prevails. diagnosis arises, the diagnosis should be based on clinicopathological features and the exclusion of other diseases.few cases can be confirmed by transbronchial biopsies; either an open-lung biopsy or a video-assisted thoracic surgical lung biopsy should be recommended.