title: Primary Ewing's sarcoma/primitive neuroectodermal tumor of the kidney. An infrequent finding.
abstract: OBJECTIVE
  Ewing's sarcoma/Primitive neuroectodermal tumor (ES/PNET) is an extraordinarily rare primary tumor in the kidney. We re-port herein the clinical, histological, and immunohisto-chemical features of a primary renal ES/PNET.
  
  
  METHODS
  A 19-year old male referred a two weeks history of constant, colic, left flank pain, and fever. A left radical nephrectomy was performed. Gross pathologic examination showed pink-tan, lobulated solid tumor, localized at the superior pole.
  
  
  RESULTS
  Histologically, the tumor was solid with necrosis. The neoplastic cells showed a small amount of clear cytoplasm, and had vesicular nuclei with small nucleoli. Immunohistochemical studies showed strongly and diffusely positive staining for CD99 in a membranous pattern.
  
  
  CONCLUSIONS
  This case represents a typical ES/ PNET affecting a young male patient. Adequate diagnosis is important because this neoplasm has an aggressive behaviour.
authors.affiliation: Department of Anatomic Pathology, Vargas Hospital, Caracas, Venezuela. parada@cantv.net
authors.forename: David
authors.initials: D
authors.lastname: Parada
authors.forename: All
authors.initials: A
authors.lastname: Godoy
authors.forename: Francisco
authors.initials: F
authors.lastname: Liuzzi
authors.forename: Karla B
authors.initials: KB
authors.lastname: Pelia
authors.forename: Aramis
authors.initials: A
authors.lastname: Romero
authors.forename: Arelí M
authors.initials: AM
authors.lastname: Parada
mesh_terms: D000328:Adult; D006801:Humans; D007680:Kidney Neoplasms / Q000473:pathology*; D008297:Male; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D018242:Neuroectodermal Tumors, Primitive / Q000473:pathology*; D012512:Sarcoma, Ewing / Q000473:pathology*