Metastatic Squamous Cell Carcinoma of the Kidney from Cholangiocarcinoma

We present a rare case of a metastatic renal tumor originating from adenosquamous carcinoma of the intrahepatic bile duct. A 64-year-old man treated with bisegmentectomy and extended cholecystectomy for cholangiocarcinoma had a left cystic renal mass, which had irregular wall thickening, heterogeneously low attenuation, and soft tissue infiltration as determined by a computed tomography scan. The first impression was renal abscess. Left nephrectomy was performed and the nonencapsulated mass was gray in color macroscopically. Histological examination of the specimen revealed alveolar proliferation of small cancer cells, which was consistent with the original tumor of the intrahepatic bile duct. The left renal tumor was misdiagnosed as a renal abscess but finally diagnosed as squamous cell carcinoma metastasized from the intrahepatic bile duct. The patient expired because of lung metastasis after 14 months following left nephrectomy. In our opinion, this case would be the first report of a renal metastasis from a cholangiocarcinoma clinically and was treated with nephrectomy.