Diffuse panbronchiolitis (DPB) is a distinct sinobronchial syndrome which has been almost exclusively reported in East Asia; only a few cases have been observed in non-Asians so far. Since 1990, when one of us described the first European case, we have screened all patients presenting with a clinical, physiopathological and radiological pattern compatible with DPB, in order to assess if the paucity of proven cases in Europe could reflect a lack of awareness of this disease among both pulmonologists and pathologists. Over a 10-years period we identified four additional DPBs, but also interestingly observed five cases of "idiopathic" bronchiolitis (IB) that had both clinical symptoms and high-resolution computed tomography (HRCT) findings indistinguishable from those of DPB, but did not show the typical histological changes. All these patients were Caucasians and presented with dyspnea, productive cough, an obstructive or mixed impairment on pulmonary function tests and chest HRCT features strongly suggesting a grade II to IV DPB. We suggest that diseases classified as IB in this study might be homogeneous entities which are clinically and radiologically similar to DPB.