title: Case report: retroperitoneal fibrosis simulating local relapse of sarcomatoid renal cell carcinoma.
abstract: BACKGROUND
  Generally, retroperitoneal fibrosis is an idiopathic process that envelopes and displaces ureters, causing hydronefrosis and renal failure. CT scan is the best choice for diagnosis. Other aetiologies described are malignancies, drugs, aorta aneurisms and immunological or rheumatological diseases.
  
  
  METHODS
  A 53-year-old male with hypertension and diabetes was operated on radical nephrectomy for renal mass. Pathological examination showed sarcomatoid renal cell carcinoma, Fürhman 3 grade, pT2 N0. Within 6 months of surgery, control CT scan demonstrated a left retroperitoneal mass, without separation with pancreas queue and spleen hilium, suggesting local relapse. Resection of the mass with splenectomy and partial pancreatectomy en bloc was performed. Microscopic evaluation revealed a dense collagenic tissue with a prominent inflammatory infiltrate, and the immunohistochemical study was negative for cytokeratin AE1-AE3. There was no evidence of malignancy in the histological examination. All these findings aided to diagnose a retroperitoneal fibrosis.
  
  
  CONCLUSIONS
  Sometimes retroperitoneal fibrosis can simulate or is associated to malignancies. Presentation of a retroperitoneal fibrosis simulating local relapse of sarcomatoid renal cell carcinoma has not been previously reported in the English literature.
authors.affiliation: Department of Urology and Pathology, Hospital Universitari Vall d'Hebron, Po Vall d'Hebron 119-129, 08035, Barcelona, Spain. doc99@erasmas.com
authors.forename: Salvador
authors.initials: S
authors.lastname: Esquena
authors.forename: José Maria
authors.initials: JM
authors.lastname: Abascal
authors.forename: Enrique
authors.initials: E
authors.lastname: Trilla
authors.forename: Inés
authors.initials: I
authors.lastname: De Torres
authors.forename: Juan
authors.initials: J
authors.lastname: Morote
mesh_terms: D002292:Carcinoma, Renal Cell / Q000175:diagnosis*; D003937:Diagnosis, Differential; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D012185:Retroperitoneal Fibrosis / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed