Large optic nerve glioma.
PB Badhe, AP Desai
Department of Pathology, Seth GS Medical College, Parel, Mumbai.
P B Badhe
Department of Pathology, Seth GS Medical College, Parel, Mumbai.
Twelve cases of optic nerve glioma seen over a 28 year period are analysed herein in this autopsy study.
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Badhe P B, Desai A P. Large optic nerve glioma. J Postgrad Med 1996;42:76-8
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Badhe P B, Desai A P. Large optic nerve glioma. J Postgrad Med [serial online] 1996 [cited 2019 Sep 23 ];42:76-8
Available from: http://www.jpgmonline.com/text.asp?1996/42/3/76/434
Optic Nerve Gliomas (ONG) are rare, constituting 1 % of all intracranial tumours. Large ONG (measuring more than 5 cms. in diameter) are even rarer. We recently had two cases of Large Optic Nerve Glioma (LONG) at the Neuropathology Department, King Edward Memorial Hospital, Bombay. The rarity of these cases has prompted us to publish this report along with ten other cases studies at our hospital, during the last 28 years.
In an autopsy study from January 1964 to December 1992, 12 cases of large optic nerve gliomas, constituting an incidence of 0.1% of the intracranial tumours studied at our hospital were encountered. A retrospective analysis of these cases forms the basis of the present report.
The gliomas, in all 12 cases, measured more than 5 cms in diameter, the largest being 9 cms. Eleven of these tumours were seen in children, with only one seen in an adult aged 24 years of age. The peak incidence, was between 5 to 7 years of age (6 cms), with a male to female ratio of 2A.
All patients presented with headache and visual impairment. Five had associated hydrocephalus; mental deterioration and proptosis was seen in two cases each. None of our cases were associated with neurofibromatosis. C T Scan was done in four cases [Figure:1]
Gross examination of the brain revealed large lobulated masses of soft consistency occupying the interpecluncular fossa [Figure:2]. The tumour arose from the optic nerve and tended to spread proximally towards the chiasma, along the nerve and its sheath. Ten of our cases showed involvement of both optic nerves and the chiasma. The right optic nerve alone was involved in one case and the left optic nerve alone in another Cut surface showed grey translucent masses with cystic degeneration and foci of haemorrhage and necrosis.
On microscopic examination the tumour showed three different patterns, with a pre-dominant spindeloid type having spindle shaped cells and bipolar processes in six cases [Figure:3]. Finely reticulated and coarsely reticulated patterns with myxomatous change was seen in two cases each. However in a single tumour. an admixture of the patterns was observed in varying proportions. Rosenthal fibres and cytoid bodies of Verhoff were seen in five cases, two showed pseudorosettes two showed occasional mitotic figures along with meningeal gliomatosis, but there was no evidence of atypia or invasion into the parenchyma. Two cases showed postoperative meningitis. Special stains like PTAH and retic were performed, which showed that the tumour was rich in glial fibrils but poor in reticulin. In one cases, a mixed oligodendroglial arid astrocytic component was observed.
Large optic nerve gliomas (LONG) are common in childhood. In our series, 11 out of 12 were children, with the peak incidence being between five to seven years. Bowler and Malson have reported a peak incidence between 26 years. The oldest reported case was 76 years of age by John R Candem., the only adult patient we encountered was 24 years of age.
Clinically and histo-pathologically, LONG belongs to a unique group of congenital glial tumours encountered in the cerebellum, medulla, corpus callosum and spinal cord but only differs from these by a frequent occurrence with neurofibromatosis. 25% of optic gliomas have associated neurofibromatosis. Stern et al observed that neurofibromatosis was more common in patients with optic nerve gliomas than in those with chiasmal glioma. Such an association was absent in our study.
Optic gliomas of adulthood seem to comprise a distinct entity with an extremely poor prognosis. Unlike these rare glioblastomas, that arise in the adult optic nerve, childhood LONG do not undergo malignant transformation and they expand without invasion of the surrounding tissue. Two mechanisms account for their growth, collateral hyperplasia of the adjacent glial and connective tissue and by the production of intra and extracellular mucosubstance which was confirmed by the ultra structural and histochemical observations using colloidal iron stains. Histologically, LONG are low grade astrocytomas,,.
Electron microscopic studies have revealed the tumour cells to be mainly astrocytes, exhibiting certain embryonic ultra structural features, but no malignant alterations have been described.
Hoyt and Baghdanarian and Glase et al reporting on cases of optic nerve and chiasmal gliomas concluded that the tumours are congenital, benign, selflimiting, hamartomatous growth,,. However, others have shown these tumours to be progressive, often leading to the patient death. Approximately, 50% to 85% of optic gliomas involve the chiasma, as was seen in our study. In general, chiasmal lesions are more aggressive and have a poorer prognosis than those confined to a single optic nerve. Rush et al reported an 85% long term survival for optic nerve tumours, compared to only a 44% long-term survival for chiasmal tumour. Although they have a more favourable prognosis, gliomas confined to the optic nerve also can progress. Wright et al reported than 8 of 17 untreated optic nerve tumours progressed. Thus, the majority of reports indicate that optic gliomas are not self limiting tumours,. Life cannot be prolonged by irradiation or transcranial procedure on the tumour.
We thank Dr (Mrs) PM Pai, Dean, Seth GS Medical College and King Edward Memorial Hospital and Dr SK Pandya, Professor and Head, Department of Neurosurgery, for granting permission to publish the material
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