Atypical clinical presentation, magnetic resonanceimaging and histopathology of ischemic opticneuropathy

Purposes: To describe an atypical clinical, diagnostic imaging and histopathological pre-sentation of an ischemic optic neuropathy in a dog. Methods: An 8-year-old female spayedBoxer was referred because of a visual concern of the left eye. Results: Ophthalmic examina-tion revealed a dark red tubular mass arising from the optic nerve into the anterior vitreous,marked papilledema and complete retinal detachment of the left eye. B-mode and Ceus-scanultrasonography could not confirm or rule out tumour aetiology. CBC, biochemistry, elec-trophoresis, coagulopathy profile and blood pressure were within normal limits. MRI showedmarked swelling of the left optic nerve, that was hypointense on T1-Weighted, hyperintenseon T2-Weighted and STIR images. The optic nerve had strong circumferential contrastenhancement extending into the chiasm. Based on the strong contrast enhancement a neo-plastic or inflammatory process was considered most likely of vascular aetiology. CSF waswithin normal limits. Based on clinical and imagining findings, a presumptive diagnosis of aneoplastic lesion was made. Exenteration was elected as the treatment and for confirmationof the diagnosis. Histopathologically a complete loss of optic nerve neural tissue (consistentwith ischemic change/infarction) was observed. Complete retinal detachment, intraretinalhaemorrhages and retinal atrophy were also present. A diagnosis of ischemic optic neuropa-thy was made. Conclusions: Optic nerve ischemia can be difficult to diagnose clinically andimaging techniques and should be included in the differential diagnoses when a dark redtubular mass is rising from the optic nerve and imagine modalities cannot exclude a vascularalteration. Confirmation is made by histopathology.