Résumé : We report the case of a 61 year old male patient presenting for exacerbated dyspnea and fatigue. He was diagnosed initially with a cavitary lung lesion one year ago but was lost to follow up since then. During the metastatic workup for the suspicious lung mass by a contrast inhanced abdominal CT-scan; a bladder lesion was found. It was resected endoscopically revealing the diagnosis of Wegener Granulomatosis which was then successfully treated by a combination of cyclophosphamide and methyl-prednisolone.