次發性的膀胱轉移腫瘤很少見。大部分病例在死後的病理解剖或癌症後期時發現。因此儘早診斷仍是一項挑戰。我們報告一罕見病例。一個六十一歲男性因為兩側腎水腫、不尋常的膀胱壁增厚及增高的癌胚抗原而會診泌尿科。雖然最初膀胱鏡檢查呈現正常膀胱黏膜外觀，經過仔細的檢查判斷，診斷出是一個肺癌之膀胱轉移的病人。雖然接受化學治療，病人於八個月後死亡。電腦斷層及膀胱鏡檢查結果的無法互相符合提供診斷上的一項重要線索。

Secondary bladder neoplasms from distant metastases are rare. Most cases are found in autopsy studies or in advanced stages. The diagnosis remains a challenge. We herein report a rare case of a 61-year-old male, who presented with bilateral hydronephrosis and thickening of the bladder wall, as well as elevated carcinoembryonic antigen. After a meticulous survey, metastatic carcinoma of the urinary bladder from the lung was diagnosed despite an initial normal appearance of the bladder mucosa on cystoscopy. The patient expired 8 months later despite treatment with chemotherapy. The incompatibility between the findings of computed tomography and the cystoscopic appearance provided an important clue for the diagnosis.