A tumor that is composed of large well-differentiated polygonal eosinophilic cells with a cytoplasm that is noted to be rather granular. A characteristic central scar can often be seen on CT or MRI. These tumors have benign histologic characteristics without necrosis or increased vascularity. The reported tumors have varied widely in size but usually are asymptomatic even when they reach a large size. The majority was discovered as an incidental finding. (ed. Walsh PC, Retik AB, Vaughn ED, Wein AJ Campbell's Urology p.2287-2289 Volume 3, 7th edition Saunders 1998)