title: Fat-forming solitary fibrous tumor of the kidney: a case report.
abstract: BACKGROUND
  Solitary fibrous tumor (SFT) arises in many parts of the body, but rarely in the kidney. To the best of our knowledge this is the second report of a fat-forming SFT in the kidney.
  
  
  METHODS
  We present a case of a fat-containing SFT at the parihilar region of the kidney in a 64-year-old man complaining of epigastric pain. The tumor was initially diagnosed as angiomyolipoma at hematoxylin and eosin stains. However, by immunohistochemistry the tumor was reclassified as a fat-forming SFT.
  
  
  CONCLUSIONS
  SFT arises in many sites, but rarely in the kidney. There is also a subset of these tumors that have a variable amount of adipocytic component that should be differentiated from angiomyolipoma. That subset of tumors affects mainly middle-aged adults of either gender and has a wide anatomic distribution. Recurrence is infrequent, and morphologically malignant examples are extremely rare.
authors: Luiz G F
authors: LG
authors: Cortes
authors: Nelson M G
authors: NM
authors: Caserta
authors: Athanase
authors: A
authors: Billis
mesh_terms: D018207:Angiomyolipoma / Q000175:diagnosis* / Q000473:pathology; D006801:Humans; D007680:Kidney Neoplasms / Q000175:diagnosis* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D054364:Solitary Fibrous Tumors / Q000175:diagnosis* / Q000473:pathology