A benign encapsulated neoplasm of the kidney, characterized by the presence of cysts separated by septa. There are no solid areas present. The septa are lined by one layer of epithelial cells that have eosinophilic or clear cytoplasm. The cystic spaces contain serous or hemorrhagic fluid. The disease is Experimental Factor Ontology id EFO_1000213 (Cystic Nephroma).