Alpha-fetoprotein-producing carcinoma of the renal pelvis exhibiting hepatoid and urothelial differentiation.

Neoplasms commonly associated with alpha-fetoprotein (AFP) production are hepatocellular carcinomas and some germ cell tumors, typically yolk sac tumor. Rare tumors of visceral origin may also be associated with AFP production and those exhibiting a distinctive morphology are now known as hepatoid adenocarcinomas. To date, eight such tumors have been reported from the bladder and a further four from the renal pelvis. We report a unique case of a mixed hepatoid adenocarcinoma and urothelial carcinoma of the renal pelvis and ureter, in which both components were found to express AFP. An 84-year-old woman with a serum AFP level of 701 ng/ml was found to have advanced high-grade renal pelvi-calyceal and ureteral urothelial carcinoma exhibiting focal hepatoid adenocarcinoma differentiation. Both components displayed strong immunostaining for AFP. The patient was treated by radical nephro-uretectomy and postoperatively the serum AFP level declined to normal at a rate commensurate with its biological half-life. The presence of AFP expression in both the urothelial and hepatoid components of the tumor suggest that the molecular pathway changes associated with AFP production precede the hepatoid differentiation of tumor cells.