title: Mesenchymal chondrosarcoma of the sellar region.
abstract: BACKGROUND
  It is known that, although rare, mesenchymal chondrosarcoma can originate intracranially. However, no such malignant tumour has been described in the sellar region.
  
  
  METHODS
  We report a case of mesenchymal chondrosarcoma in a 21-year-old man who presented with double vision, right blepharoptosis and facial pain. Upon initial admission, no endocrinological abnormalities were found, and computed tomography and magnetic resonance imaging revealed a mass with calcification in the sella and right cavernous sinus.
  
  
  METHODS
  For this malignant tumour, three surgical resections, two sessions of gamma-knife radiosurgery, one session of fractional irradiation, and one cycle of chemotherapy were performed, resulting in only brief arrest of the tumour growth. Pathologically, the tumour consisted of undifferentiated small cells of high cellularity, and islands of hyaline cartilage. The undifferentiated small cells showed immunoreactivity for vimentin and ultrastructural features suggesting a mesenchymal origin. Lacunar cells in the islands were immunopositive for S-100 protein and vimentin.
  
  
  CONCLUSIONS
  Although malignant tumours in the sellar region are rare, they should be considered in the differential diagnosis of various sellar tumours typified by non-functioning pituitary adenoma, and mesenchymal chondrosarcoma is one possible candidate.
authors.affiliation: Department of Pathology, Brain Research Institute, Niigata University, Japan. inenaga@bri.niigata-u.ac.jp
authors.forename: C
authors.initials: C
authors.lastname: Inenaga
authors.forename: K
authors.initials: K
authors.lastname: Morii
authors.forename: T
authors.initials: T
authors.lastname: Tamura
authors.forename: R
authors.initials: R
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Takahashi
mesh_terms: D000328:Adult; D001859:Bone Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy; D018211:Chondrosarcoma, Mesenchymal / Q000000981:diagnostic imaging / Q000473:pathology* / Q000628:therapy; D006801:Humans; D008297:Male; D011859:Radiography; D012658:Sella Turcica / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery