title: Extrarenal Wilms tumour.
abstract: BACKGROUND
  Nephroblastoma is one of the most common solid tumours in children. It also is the most frequent tumour found in the kidneys. In 5 % of cases it affects both kidneys at the same time. About 70 - 80 new cases of Wilms tumour are registered in Poland annually, usually in patients aged from 1 to 7 years. Extrarenal Wilms tumours are extremely rare. Due to its rarity, series with more cases are based upon material collected from many clinical centers.
  
  
  OBJECTIVE
  We would like to present a case of a boy in whom we diagnosed nephroblastoma in the retroperitoneal space 14 years after he had completed a complex therapy for bilateral Wilms tumour.
  
  
  CONCLUSIONS
  The development of an extrarenal tumour 14 years after complex treatment for bilateral nephroblastoma is related to the survival of metanephros located outside the kidney.
authors.affiliation: Department of Paediatric Surgery and Urology, University of Medicine, Wrocław, Poland.
authors.forename: W
authors.initials: W
authors.lastname: Apoznański
authors.forename: K
authors.initials: K
authors.lastname: Sawicz-Birkowska
authors.forename: W
authors.initials: W
authors.lastname: Pietras
authors.forename: U
authors.initials: U
authors.lastname: Dorobisz
authors.forename: T
authors.initials: T
authors.lastname: Szydełko
mesh_terms: D000293:Adolescent; D006801:Humans; D007668:Kidney / Q000196:embryology*; D007680:Kidney Neoplasms / Q000601:surgery*; D016609:Neoplasms, Second Primary / Q000175:diagnosis* / Q000601:surgery*; D012186:Retroperitoneal Neoplasms / Q000175:diagnosis* / Q000601:surgery*; D013997:Time Factors; D009396:Wilms Tumor / Q000175:diagnosis* / Q000601:surgery