title: Presacral extrarenal Wilms tumor in a child.
abstract: OBJECTIVE
  Wilms tumor (WT) is one of the most common solid tumors in children. It also is the most frequent tumor found in the kidneys. In 5% of cases, it affects both kidneys simultaneously. Extrarenal WTs are extremely rare. The diagnosis of extrarenal WT is almost always made after surgical intervention. The tumor can be located in the retroperitoneum, uterus, cervix, testes, skin, and even the thorax.
  
  
  METHODS
  We report on a 3-year-old girl with an extrarenal WT located in the presacral region.
  
  
  RESULTS
  The exact mechanism whereby a WT occurs in extrarenal tissues is unknown. The presence of ectopic metanephric blastema cells or the WT gene causing transformation of extrarenal primitive mesonephric or pronephric remnants into WT have both been considered in the embryogenesis. Although imaging examinations are helpful in the definition of retroperitoneal tumors, no characteristic findings are available to diagnose an extrarenal WT before surgery.
  
  
  CONCLUSIONS
  As a rule, the diagnosis of extrarenal WT is made after surgery. Surgical excision is the treatment of choice and the same general therapeutic rules should be followed as when the kidney has been affected. The use of Stage III guidelines for chemotherapy and radiotherapy are appropriate for these patients.
authors.affiliation: Department of Pediatric Surgery, Affiliated Shengjing Hospital of China Medical University, Heping District, ShenYang, Liaoning, People's Republic of China.
authors.forename: Hui Min
authors.initials: HM
authors.lastname: Jia
authors.forename: Ke Ren
authors.initials: KR
authors.lastname: Zhang
authors.forename: Hong
authors.initials: H
authors.lastname: Shu
authors.forename: Bao Ling
authors.initials: BL
authors.lastname: Tian
authors.forename: Wei Lin
authors.initials: WL
authors.lastname: Wang
mesh_terms: D002675:Child, Preschool; D005260:Female; D006801:Humans; D012186:Retroperitoneal Neoplasms / Q000175:diagnosis / Q000601:surgery; D012445:Sacrococcygeal Region; D009396:Wilms Tumor / Q000175:diagnosis / Q000601:surgery