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Optic Pathway Glioma




Hereditary Factors


Optic tract gliomas are linked to the hereditary disorder neurofibromatosis type 1 (NF1)

  • Commonest type of neurofibromatosis (about 80%)
  • Also called von Recklinghausens disease.
  • Autosomal dominant hereditary disorder.
  • In half of all patients there is a family history and half have a spontaneous mutation.
  • Severity  of symptoms varies significantly between different individuals (variable expression).
  • The NF1 gene has been mapped to chromosome 17q11.2.
  • NF1 is associated with the development of:
    • optic nerve gliomas
    • other CNS tumors
    • soft tissue sarcomas (malignant peripheral nerve sheath tumors) later in life

Two of the following must be present to make the diagnosis of NF1.

  • Optic nerve glioma
  • Axillary freckling (Crowe’s sign)
  • Café –au-lait spots (six or more and have to be over 0.5 cm in children and over 1.5 cms in adults)
  • Two or more neurofibromas and one plexiform neurofibroma
  • Two or more hamartomas of the iris (Lisch nodules)
  • First degree relative affected with NF1
  • Bony lesion – thinning of long bone cortex or sphenoid dysplasia.

Optic Nerve Gliomas in NF1

  • 25-40% of optic gliomas occur in children with NF.
  • Up to 15% of MR/CT scans of children with NF who have no visual or ocular abnormalities reveal optic gliomas.
  • Bilateral tumors are invariably associated with NF-1, so the diagnosis of NF has been extended to include the presence of a bilateral intraorbital optic glioma.
  • The new diagnosis of an optic glioma in a child should prompt investigation of other family members for NF/optic pathway gliomas.
  • The biological behavior of optic pathway gliomas (OPG) associated with NF1 are different from OPG without NF.  With NF 1:
    • The course of the disease is variable - patients with NF are often asymptomatic and tumors do not progress for long time periods. 
    • There have been some documented cases of spontaneous regression.
  • Tumors in children with NF 1 tend to have a circumferential perineural growth pattern, whereas those that present without NF 1 have a more expansive interneural growth pattern.


Below is a MR (axial flair image) that demonstrates bilateral signal changes of uncertain etiology (#1 point to these areas) commonly seen in pediatric patients with NF1.

Below is a MR (Sag Postcontrast T1 image) demonstrating a nerve sheath tumour (#2). This is likely a neurofibroma within the vertebral canal, located anterior to and compressing the spinal cord.



Neurofibromatosis type 1 (NF1): Atlas of Genetics and Cytogenetics in Oncology and Haematology

Neurofibromatosis at DermAtlas




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