Microcystic Meningioma of the Fourth Ventricle in a Dog

Abstract

ABSTRACT. A 5-year-old female cross-breed dog was presented with a 1-month history of progressive changes in the posture of the head and in the gait. At neurological examination the dog showed a central vestibular syndrome lateralized to the left. MRI showed a space occupying lesion within the fourth ventricle, characterized by iso-to hypointensity in T1 and hyperintensity in T2 with a heterogeneous contrast uptake. Histologically, a neoplasia composed of meningothelial cells forming compact whorls with slight atypia, and stellate cells delimitating microcysts containing eosinophilic fluid was observed. Neoplastic cells were positive for vimentin and negative for GFAP and FVIII. A diagnosis of intraventricular microcystic meningioma was achieved. Intraventricular meningiomas in dogs are rarely encountered and reports of meningiomas within the fourth ventricle have not yet been described. Although choroid plexus tumor is the most frequent neoplasia localized in the fourth ventricle, intraventricular meningioma should be included in the differential diagnoses.KEY WORDS: canine, central nervous system tumors, intraventricular meningioma, microcystic meningioma.J. Vet. Med. Sci. 73(3): 367-370, 2011 Meningiomas are the most common canine intracranial tumors and differently from human neuro-oncology are frequently classified as atypical meningioma (grade II) with a poorer therapeutic response [14]. Meningiomas involve most commonly the anterior half of the dorsal surface of the brain near the falx [11]. Other common locations are tentorium cerebelli, ventral or lateral aspect of the brainstem, mainly at hypothalamus and optic chiasm level, and other external surfaces of the brain with a typical extra-axial growth pattern [9,11]. Although the intraventricular location involving the tela choroidea of the third ventricle represents a common site for meningiomas in cats [15], it is rare in dogs and the presence of meningiomas in the fourth ventricle has not yet been described in the literature. A secondary involvement of the fourth ventricle by a meningioma consequent to local extension has been described in a dog [6]. In human beings, intraventricular meningiomas are rare and meningiomas of the fourth ventricle are exceptional [4].Histologically, meningiomas in animals are classified as meningothelial, fibroblastic, transitional, psammomatous, angiomatous, papillary, granular cell, myxoid and anaplastic [5]. Rare reports of cystic and microcystic meningiomas are also described [1,8,12,14].To our knowledge, no cases of microcystic meningiomas involving the fourth ventricle in dogs have been described so far. This report describes the clinical, neuroradiological and neuropathological findings of a dog with a primary meningioma of the fourth ventricle with histological features suggestive of microcystic subtype.A 5-year-old female cross-breed dog was presented with a 1-month history of progressive changes in the head posture, frequent fallings, circling to the left side and excessive anxiety. Neurological evaluation rev...

High‐grade astrocytoma with ventricular invasion in a dog

“…Although there is an increased risk for the development of gliomas in brachycephalic breeds, such as Boxers and Boston terriers, other breeds can also be affected 3 4 6 9. As in the present case, the clinical signs of CNS neoplasms tend to evolve slowly and progressively,13 and changes in mentation are one of the most common clinical signs 3…”

“…Given the tumour location, the main differential diagnoses were an ependymal tumour (ependymoma), which often occurs in the lateral ventricles, a choroid plexus tumour (choroid plexus papilloma, atypical choroid plexus papilloma or choroid plexus carcinoma),3 9 13 14 which occurs mainly in the fourth ventricle,15 and, less likely, an oligodendroglioma7 or a meningioma 13…”

Meningiomas em cães: aspectos clínicos, histopatológicos e imuno-histoquímicos

“…A expressão do fator VIII foi negativa em todos os tumores (Quadro 2), contribuindo com o diagnóstico diferencial ao excluir tumores de origem vascular (Salvadori et al 2011). Os resultados obtidos na análise imuno-histoquími-ca são semelhantes aos descritos em estudo prévio (Barnhart et al 2002).…”

Canine Primary Intracranial Cancer: A Clinicopathologic and Comparative Review of Glioma, Meningioma, and Choroid Plexus Tumors

“…Meningothelial and transitional subtypes represent anywhere from 20 to 30% or higher of meningioma incidence (119). Microcystic meningiomas are also a relatively common subtype in the dog and have large, variably sized vacuoles that develop in the neoplastic cells that can often coalesce to form large cysts within the tumor (120). In this rare instance, the gross texture of a microcystic meningioma is more fluctuant than the more common firm texture.…”