title: Primary and metastatic renal hemangiopericytoma.
abstract: OBJECTIVE
  Haemangiopericytoma is an uncommon perivascular tumor that occurs more frequently in soft tissues and is extremely rare in the kidney.
  
  
  METHODS
  We report two cases: The first one is the case of a 57-year-old man with bilateral metastatic renal haemangiopericytoma which appeared 18 years after removal of a meningeal haemangiopericytoma. The second is a 29-year-old woman with a primary kidney haemangiopericytoma that was casually found in a nephrectomy piece.
  
  
  RESULTS
  In the first case, radical left nephrectomy and right renal mass radiofrequency ablation were performed. The patient had an uneventful postoperatory recovery. He remained disease-free 22 months after surgery but two new lesions appeared that were treated with radiofrequency ablation. The second case was a casual finding, a small tumor that had been totally resected.
  
  
  CONCLUSIONS
  Haemangiopericytoma is a rare tumor with an uncertain clinical behaviour. Long-term follow up is important as local recurrences and metastases can develop years after initial treatment.
authors.affiliation: Urology Department. Hospital Clínico Universitario Valladolid. Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Martín Martín
authors.forename: Juan Ramón
authors.initials: JR
authors.lastname: Torrecilla Garcia-Ripoll
authors.forename: Francisco Javier
authors.initials: FJ
authors.lastname: Trueba Arguiñarena
authors.forename: Jose Ramon
authors.initials: JR
authors.lastname: Cortiñas Gonzalez
mesh_terms: D000328:Adult; D005260:Female; D006393:Hemangiopericytoma / Q000175:diagnosis / Q000601:surgery; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D009392:Nephrectomy