Faecal Occult Blood Test

Case of the Month (Emma Scurrell November 2011)

Optic nerve glioma a dog

An 11-year-old male Labrador presented with unilateral blindness associated with intraocular haemorrhage and glaucoma. No further diagnostics were performed and enucleation was performed. The clinician noted that the optic nerve appeared grossly thickened.



 Fig 1. The globe has been sectioned in half. The optic nerve is thickened (red arrow) and replacing the optic nerve head is a firm white tumour which protrudes into the vitreous (blue arrow). The adjacent choroid is mottled white-brown consistent with tumour invasion. The retina is detached (white arrows) and there is intraocular haemorrhage.


Fig 2.  Immunostaining for GFAP (glial fibrillary acidic protein) reveals strong immunopositive brown staining of the tumour cells which supports astrocytic origin (x200). 

 


 






Final Diagnosis

Optic nerve glioma (astrocytoma).

Discussion

Gliomas are neoplasms which arise from glial cells (e.g. astrocytes and oligodendrocytes). They most commonly occur in the brain and spinal cord however in rare cases, they may also arise in the optic nerve or retina. Infiltrative behaviour is typical but the risk of metastasis (e.g. to the lungs) is low. The concern in this particular case would be local recurrence at the level of the transected optic nerve and spread along the optic nerve tract. Seeding via the CSF to other areas of the brain is also a possibility. The tumour in this case is associated with choroidal invasion, retinal detachment and intraocular haemorrhage, the last two of which predispose to the formation of pre-iridal fibrovascular membranes which form along the anterior face of the iris and extend into the drainage angle resulting in secondary glaucoma.

Previous Monthly Cases

Hypertensive Retinopathy January 2010
FIP in a cat - uncommon presentation February 2010
Phaeohyphomycosis    March 2010 
Scleral Rupture April 2010
Canine and feline epulides May 2010
Erythema multiforme in a labrador retreiver June 2010
Keloidal fibrosarcoma in a labrador retreiver July 2010
Cutaneous epitheliotropic lymphoma  August 2010 
Benign cutaneous histiocytoma  September 2010 
Iridociliary adenoma October 2010
Proliferative thrombovascular necrosis of the pinnae November 2010
Signet-ring cell carcinoma in the stomach of a dog December 2010
Cutaneous infiltrative lipoma in a labrador January 2011

Tonsillar squamous cell carcinoma February 2011
Canine orbital meningioma March 2011
"Lung-digit" syndrome in a cat April 2011
Hepatic amyloidosis in a cat May 2011
Haemophagocytic histiocytic sarcoma June 2011
Alternaria spp. infection in an immunocompromised dog July 2011
Ocular manifestation of lymphoma in a cat  August 2011
Kerion dermatophytosis in a Cocker spaniel September 2011
Subcuticular coenurus in a rabbit  October 2011



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Faecal Occult Blood Test