title: Clival dedifferentiated chordoma: a case report.
abstract: BACKGROUND
  Chordoma is a rare, slowly growing tumor arising from notochordal rests and occurring in several anatomical locations with different clinical patterns of presentation. Dedifferentiation or sarcomatous transformation in a chordoma is a known but rarely recorded event.
  
  
  METHODS
  We report the case of a 58-year-old man diagnosed with chordoma of the clivus who, over the course of 5 years, showed histological and immunohistochemical evidence of progressive dedifferentiation in the tumor.
  
  
  CONCLUSIONS
  Sarcomatous transformation in chordomas is seen less frequently in the clival region. A high degree of suspicion and extensive sampling are essential for diagnosis, especially in recurrent tumors.
authors: Nikhil
authors: N
authors: Rabade
authors: Naina
authors: N
authors: Goel
authors: Atul
authors: A
authors: Goel
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D054337:Cell Dedifferentiation; D002817:Chordoma / Q000000981:diagnostic imaging* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D011859:Radiography