Canine orbital meningiomas: a review of 22 cases

Abstract

Clinical and pathologic features of primary orbital meningiomas in the dog were reviewed. Twenty‐two meningiomas, confined to the orbit, were identified from the Comparative Ophthalmic Pathology Laboratory of Wisconsin from 1981 to 1997. The dogs ranged in age from 3 to 17 years (mean = 9.2 years). The clinical presentation, reported in 20 cases, was indicative of a retrobulbar mass and included exophthalmos and orbital swelling (18/20), and papilledema or abnormalities of the posterior segment (7/20). Visual acuity was reported in 15 cases; of those, 12 dogs were blind in the affected eye. Follow‐up information was obtained on 17 cases; six dogs developed local recurrence of the neoplasm. Two dogs with recurrent neoplasms simultaneously developed blindness in the opposite eye. Extension along the optic nerve to the optic chiasm was suspected. No metastasis was found at the time of the study. Enucleation with excisional biopsy was effective therapy to date in 11 cases (0.2–4.5 years follow‐up time). All neoplasms were located within the vicinity of the optic nerve and, when sectioned through the optic nerve head, appeared to completely envelope the nerve. The neoplastic cells were arranged in tight whorls and bundles characteristic of meningiomas. Most tumors had islands of chondroid and osseous metaplasia (17/22). Ocular invasion was limited to small foci in the posterior choroid or optic nerve head of six dogs. Immunoperoxidase stains on 10 cases were positive for vimentin and S‐100, but negative for cytokeratin. Electron microscopy revealed complex interdigitations between cell membranes and few desmosomal intercellular attachments. Primary orbital meningiomas have a characteristic histologic appearance and may recur locally after surgical excision.

Immunohistochemical Detection of CD34, E-cadherin, Claudin-1, Glucose Transporter 1, Laminin, and Protein Gene Product 9.5 in 28 Canine and 8 Feline Meningiomas

“…1,3,22,27,30,33,41 In our series, transitional meningioma was the most common type in dogs, but psammomatous meningioma was the most common type in cats. Meningiomas in cats tend to occur at a later age than do those in dogs.…”

Ocular Granulomatous Meningoencephalomyelitis in a Dog: Magnetic Resonance Images and Clinical Findings

“…Gliomas and meningiomas of the optic nerves have also been reported in dogs [16]. These tumors occasionally cause swelling of the optic nerves and/or chiasm [14,16]. Although our dog showed swelling of the chiasm, the optic nerves were not swollen.…”

Clinicopathologic findings in a dog with a retrobulbar meningioma

“…12,20,21 Grossly, retrobulbar meningiomas commonly appear as conical, solid tan to slightly granular masses, which are tightly adhered to the posterior aspect of the globe and taper along the nerve as it approaches the optic canal. 12,21 Retrobulbar meningioma is a rare neoplasm but has been reported previously in human beings, 19 dogs, 3,10,13,22,24,25,27 a cat, 1 and cattle. 30 Meningiomas in dogs are histologically diverse and display highly variable morphologic patterns.…”

“…1 Of the primary orbital tumors, retrobulbar meningioma is a common nervous system tumor that arises from the meninges, which cover the optic nerve within the orbit. 24 Regardless of the disease process, clinical signs often consist of exophthalmia, decreased retropulsion of the globe, blindness, orbital swelling leading to a prolapsed globe, incomplete palpebral closure, strabismus, elevation of the membrana nictitans, pain on opening the mouth, visual deficits, and abnormalities in the pupillary light reflex (PLR). 31 Ophthalmic examination may disclose papilledema, retinal edema, and scleral indentation.…”