title: Choristoma of the optic nerve: case report.
abstract: OBJECTIVE
  Optic nerve choristoma is a rare lesion composed of adipose tissue and smooth muscle involving the optic nerve. Few cases have been reported.
  
  
  METHODS
  A 20-year-old woman presented with a history of slowly progressive visual loss in the left eye. On T1-weighted magnetic resonance imaging studies, after frequency-selective fat saturation, an optic nerve mass was detected at the level of the optic canal with signal characteristics suggesting the diagnosis of optic nerve lipoma.
  
  
  METHODS
  At left frontotemporal craniotomy, the intracranial optic nerve appeared thin and atrophic proximally and was covered by abundant adipose tissue distally. Because no cleavage plane could be identified between the fatty lesion and the optic nerve, which appeared splayed within the adipose tissue, the nerve was resected after an intraoperative biopsy. The presence of two heterotopic mesodermal elements, a rim of adipose tissue admixed with bundles of mature smooth muscle, extending into the nerve septa, warranted a diagnosis of optic nerve choristoma.
  
  
  CONCLUSIONS
  Optic nerve choristoma is an uncommon optic nerve lesion. Even if imaging studies are highly suggestive of the diagnosis, pathological confirmation is required because of the high adipose tissue content in the majority of cases. The lesion, most likely malformative and nonneoplastic in nature, can be the cause of progressive visual loss.
authors: Department of Pathology, Mayo Clinic, Rochester, Minnesota 55905, USA. Giannini.Caterina@Mayo.edu
authors: Caterina
authors: C
authors: Giannini
authors: Carol
authors: C
authors: Reynolds
authors: Jacqueline A
authors: JA
authors: Leavitt
authors: Gregory A
authors: GA
authors: Schultz
authors: James A
authors: JA
authors: Garrity
authors: Michael J
authors: MJ
authors: Ebersold
authors: Bernd W
authors: BW
authors: Scheithauer
authors: Diva R
authors: DR
authors: Salomao
mesh_terms: D000293:Adolescent; D002828:Choristoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D005260:Female; D006801:Humans; D019574:Optic Nerve Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery