RT Journal Article SR Electronic T1 Fat-forming Solitary Fibrous Tumor of the Kidney – A Case Report and Literature Review JF In Vivo JO In Vivo FD International Institute of Anticancer Research SP 649 OP 652 VO 32 IS 3 A1 NICOLAE BACALBASA A1 IRINA BALESCU A1 GEORGE JINESCU A1 MADALINA MARCU A1 ANDREEA CONTOLENCO A1 DOINA POP A1 DRAGOS DOBRITOIU A1 OLIVIA IONESCU A1 PARIS IONESCU A1 CLAUDIA STOICA YR 2018 UL http://iv.iiarjournals.org/content/32/3/649.abstract AB Fat-forming solitary fibrous tumors arising from the kidney are extremely rare, with only few cases reported so far. We report the case of a 49-year-old patient investigated for lumbar pain and diagnosed preoperatively with a large retroperitoneal tumor destroying the right kidney. The patient was submitted to surgery, the tumor being resected en bloc with right nephrectomy. The histopathological studies demonstrated the presence of a hemangiopericytoma-like tumor with adipocytary component; the immunohistochemical studies demonstrated the presence of cluster of differentiation 34 (CD34), while human melanoma black (HMB45) staining was negative. Therefore, the diagnostic of fat-forming solitary fibrous tumor of the kidney was established. The postoperative outcome was uneventful, the patient being discharged on the sixth postoperative day. In conclusion, although fat-forming solitary fibrous tumor of the kidney is a very rare entity, this diagnosis should be taken into consideration whenever a large retroperitoneal mass with high adipose content and renal invasion is described at the preoperative studies.