Metastatic biliary polypoid thrombus from renal cell carcinoma: report of a case.

We report an extremely rare case of metastatic biliary polypoid thrombus with hepatic metastases from renal cell carcinoma. A 74-year-old man was admitted with a low-grade fever and obstruction of the left hepatic duct. He had undergone left nephrectomy 17 years previously due to a diagnosis of renal cell carcinoma. A preoperative diagnosis of left hepatic duct carcinoma was made, and a left lobectomy and left caudate lobectomy with right biliary anastomosis of jejunal loop were performed. The resected specimen showed a polypoid mass in the left hepatic duct with metastases in the caudate lobe, and a histological examination revealed both tumors to be clear cell-type renal cell carcinoma. The mechanism of biliary metastatic thrombus formation was speculated to be as follows: caudate lobe metastases invade the adjacent bile ducts, and a tumor fragment in the bile duct then becomes implanted in the intraluminal left hepatic duct, thus leading to the growth of the biliary polypoid thrombus.