These tumors are often associated with a history of end-stage renal disease and acquired cystic kidney disease, most commonly in patients on long-term hemodialysis. They are often bilateral, multifocal lesions with well-defined borders and a background of surrounding polycystic kidneys. The histology is characterized by microcystic structures and abundant eosinophilic oxalate crystals within the tumor. Immunohistochemistry was positive for renal cell carcinoma, CD10 and AMACR, and negative for CK7.