Abstract

Adult Wilms' tumor, unlike that of childhood, is a rare disease. Microscopically, the tumor is fundamentally characterized by triplastic embryonal renal tumor composed of variable amounts of metanephric blastema and its epithelial and stromal derivatives but rarely a small group of tumors composed virtually entirely of differentiated epithelial derivatives, the abundance of tubular structures. These monomorphous epithelial type of Wilms' tumor tended to have an early onset and benign course. Grossly, classic Wilms' tumor is a solid tumor, but very rarely shows cystic change and may lead to misinterpretation as a polycystic kidney or multicystic nephroma. Here, we reports a case of primary renal tumor, grossly very similar to a multicystic kidney but histologically represent a tubular monomorphous epithelial variant of Wilms' tumor occured in 63 year old male adult.