title: Optic nerve glioma: A great mimicker.
abstract: BACKGROUND
  Arachnoid proliferation, although rare, is known to occur in association with optic gliomas. However, chondroid and chordoid metaplasia has not been reported previously.
  
  
  METHODS
  A 27-year-old male presented with progressive, painless loss of vision in right eye, associated with vomiting and headache for one and a half months. Computed tomography (CT) scan revealed a contrast enhancing mass arising from planum sphenoidale. Perioperative findings showed the tumor adherent to the right optic nerve and attached to basal dura and falx. A clinical impression of an intradural, optic nerve sheath meningioma was made. Histopathological examination revealed a glial tumor with adjacent areas displaying marked fibroblastic and arachnoid cell proliferation with chondroid as well as chordoid differentiation along with myxoid change and dense collagenisation. Reticulin stain, immunochemistry with glial fibrillary acid protein (GFAP), epithelial membrane antigen (EMA), and S-100 helped to arrive at the final diagnosis of optic glioma displaying exuberant arachnoid proliferation with cartilaginous metaplasia.
  
  
  CONCLUSIONS
  We report a case of optic nerve glioma displaying extensive arachnoid proliferation, chordoid, and cartilaginous metaplasia, which mimicked chondrosarcoma or chordoid meningioma, posing a diagnostic dilemma. A clinical feedback, simple reticulin stain, and GFAP staining is of immense value in such cases to arrive at the correct diagnosis.
authors.affiliation: Department of Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Poonam
authors.initials: P
authors.lastname: Bhaker
authors.affiliation: Department of Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Ruchita
authors.initials: R
authors.lastname: Tyagi
authors.affiliation: Department of Radiodiagnosis, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Divyesh
authors.initials: D
authors.lastname: Mahajan
authors.affiliation: Department of Neurosurgery, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Mohindra
authors.affiliation: Department of Pathology, Post Graduate Institute of Medical Education and Research, Chandigarh, India.
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Vasishta
keywords: Arachnoid hyperplasia; chondroid; chordoid; glioma; optic nerve