Review ArticlesCystic Renal Tumors: New Entities and Novel ConceptsMoch, Holger MD Author Information Department Pathology, University Hospital Zurich, Switzerland Reprints: Holger Moch, MD, Department Pathology, Institute for Surgical Pathology, University Hospital Zurich, Schmelzbergstr. 12, CH-8091 Zurich, Switzerland (e-mail: [email protected]). All figures can be viewed online in color at http://www.anatomicpathology.com. Advances in Anatomic Pathology: May 2010 - Volume 17 - Issue 3 - p 209-214 doi: 10.1097/PAP.0b013e3181d98c9d Buy Metrics Abstract Cystic renal neoplasms and renal epithelial stromal tumors are diagnostically challenging and represent some novel tumor entities. In this article, clinical and pathologic features of established and novel entities are discussed. Predominantly cystic renal tumors include cystic nephroma/mixed epithelial and stromal tumor, synovial sarcoma, and multilocular cystic renal cell carcinoma. These entities are own tumor entities of the 2004 WHO classification of renal tumors. Tubulocystic carcinoma and acquired cystic disease-associated renal cell carcinoma are neoplasms with an intrinsically cystic growth pattern. Both tumor types should be included in a future WHO classification as novel entities owing to their characteristic features. Cysts and clear cell renal cell carcinoma frequently coexist within the kidneys of patients with von Hippel-Lindau disease. Sporadic clear cell renal cell carcinomas often contain cysts, usually as a minor component. Some clear cell renal cell carcinomas have prominent cysts, and multilocular cystic renal cell carcinoma is composed almost exclusively of cysts. Recent molecular findings suggest that clear cell renal cancer may develop through cyst-dependent and cyst-independent molecular pathways. © 2010 Lippincott Williams & Wilkins, Inc.