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Background: Dogs and cats are the most common domestic animal species diagnosed with primary neoplasms of the central nervous system. Of these, meningioma is the brain tumor most commonly reported in dogs and is associated with several neurological changes, such as seizures. The ante mortem diagnosis is difficult to make because the use of computerized tomography, the gold standard for the presumptive diagnosis of brain tumors, is still a limited and expensive exam in veterinary medicine. The aim of this study is to report the case of a grade II transitional meningioma in a female dog attended and necropsied at the Veterinary Hospital of the Universidade Estadual de Santa Cruz (HV-UESC). Case: A 13-year-old female Poodle was examined at HV-UESC with a clinical history of prostration, apathy, anorexia, partial vision loss, and neurological abnormalities, including seizures. The dog was being treated with phenobarbital (2 mg/ kg three times a day) for seizures and doxycycline (5 mg/kg twice a day) for anaplasmosis diagnosed prior to clinical care at HV-UESC. On physical examination, the dog was observed to be mentally altered, with increased aggression, walking in large circles to the left, tremors and spasticity of the thoracic limbs. Laboratory analysis revealed a normal complete blood count. Biochemical analysis revealed an increase in alanine aminotransferase (296 U/mL), alkaline phosphatase (286 U/ mL) and urea (121 mg/dL) levels. Based on the clinical and laboratory abnormalities, the suspicion of cerebral degenerative neuropathy or neoplasia was established. The dog was examined again approximately two months after initial presentation and no improvement in the dog's neurological condition was noted; in fact, the dog's condition had deteriorated, which was evidenced by worsening seizures, tetraparesis and bedsores. Due to the severity of the neurological changes, euthanasia was performed. After authorization from the owner, the dog was referred to the HV-UESC Necropsy Department, where the dog was necropsied. The primary macroscopic finding was a well-defined mass measuring approximately 2.5x1.5x1.5 cm in the frontal cortex of the left cerebral hemisphere. The lesion was firm and white with an irregular surface and was adhered to the dura mater. The mass compressed the adjacent brain tissue. Histopathological analysis demonstrated a non- encapsuled, expansive, and partially delimited neoplasm characterized by sheets of meningoendothelial cells arranged primarily in mantles, though sometimes in lobes, in two distinct patterns: meningoendothelial and fibrous. In addition, a moderate amount of psammomatous bodies were observed. These microscopic characteristics led to the diagnosis of a grade II transitional meningioma. Discussion: This report describes a case of meningioma in a female dog, which is the most common type of brain tumor diagnosed in dogs according to the literature. The affected animal was advanced in age, a factor that is associated with an increased risk of developing this neoplasm. The neurological alterations noted in this report were associated with the neoplastic process. The macroscopic finding of a cerebral neoformation was suggestive of neoplasm; this was confirmed by microscopic evaluation of the mass. As has been previously reported, the clinical neurological signs of most cases of suspected brain tumors occur late in the disease process, at which point the neoplasm is already in an advanced stage of development. Thus, the prognosis of the affected animal is poor, as it was in this case, which leads to euthanasia. In summary, this is a report of a case of intracranial transitional meningioma accompanied by progressive neurological alterations, in which an ante mortem diagnosis is difficult due to the limited use of computerized tomography in routine veterinary practice. [ABSTRACT FROM AUTHOR]

The purpose of this retrospective, multicentre case series was to describe the outcome following surgery and/or radiation of spinal meningiomas and nerve sheath tumours (NSTs) based upon treatment modality, with a specific aim to evaluate the survival times and time to recurrence following treatment for each histopathological diagnosis. Our hypothesis was that the addition of radiation therapy modalities to treatment will yield longer time to recurrence of clinical signs and survival time. Thirty‐four dogs met the inclusion criteria of histopathologically diagnosed extramedullary spinal meningioma or NST. Sixteen extramedullary spinal meningiomas and 18 NSTs were diagnosed. A diagnosis of meningioma was associated with a significantly longer survival time compared with NSTs, with median survival times (MST) of 508 days (95% confidence interval [CI]: 66‐881) vs 187 days (95% CI: 76‐433; P = .02). Dogs (seven) treated with stereotactic radiation therapy (SRT) for recurrence after surgery alone or SRT alone as their initial treatment gained an additional 125 to 346 days survival time. [ABSTRACT FROM AUTHOR]

Cutaneous meningiomas are rare tumors in human beings and animals. Two canine cases of cutaneous meningiomas affecting the eyelid are described in the current study: the first from a 5-week-old female Springer Spaniel dog with an 8 cm in diameter congenital mass expanding the left upper eyelid and medial canthus; the second from a 10-year-old female spayed Maltese–Poodle mix dog with 3 firm subcutaneous nodules affecting the right upper eyelid. All masses were removed surgically. Histologically, tumors were composed of spindle-to-epithelioid cells arranged in small lobules forming solid concentric whorls. Neoplastic cells were positive for vimentin and S100 and negative for pancytokeratin, glial fibrillar acid protein, and neurofilament. Transmission electron microscopy revealed meningothelial cells with convoluted interdigitating processes, desmosomes, and hemidesmosomes, and moderate numbers of cytoplasmic microfilaments. None of the cases presented a primary neuroaxial meningioma. The first case presents clinicopathological features consistent with human type I (congenital) cutaneous meningioma. The second case is consistent with a type II (acquired ectopic) tumor, and both are hypothesized to arise from ectopic arachnoid cells displaced during development. [ABSTRACT FROM PUBLISHER]

Matrix metalloproteinases (MMPs) are proteolytic enzymes involved with extracellular matrix degradation. They have been considered to be important for tumor growth and development of peritumoral edema. This retrospective study investigated the expression of MMP subtypes 9 and 2 in canine intracranial meningiomas and their association with peritumoral edema. Twenty-two cases of histologically confirmed grade I meningiomas based on human World Health Organization classification were enrolled. Tumor volume and peritumoral edema were measured by magnetic resonance imaging volumetry. The intratumoral MMP expression was semiquantitatively assessed by immunoreactivity scores and compared with the imaging data. MMP-9 was expressed in all the samples (22/22), whereas proMMP-2 was expressed in 21 of 22 meningiomas, and a/proMMP-2 was expressed in 9 of 22. The immunoreactivity scores were not statistically linked to the severity of peritumoral edema. None of the evaluated MMP expression parameters were statistically linked to the edema index. Although both edema index and MMP-9 expression were highest in meningiomas of the olfactory and frontal region, only the latter mounted up to statistical significance (P = .002) if compared with parafalx and convexity meningiomas of the parietal lobe. In summary, MMP-2 and MMP-9 expression by tumor cells, evaluated through immunohistochemistry, is not predictive of the formation of peritumoral edema in canine rostrotentorial meningiomas. [ABSTRACT FROM PUBLISHER]

The article presents a case study of a female cross-breed dog with microcystic meningioma of the fourth ventricle. The dog presented with progressive changes in the head posture and gait. A central vestibular syndrome lateralized to the left was identified through neurological examination. A lesion within the fourth ventricle was detected through magnetic resonance imaging (MRI). Neoplastic cells were found to react positively with vimentin and negatively with glial fibrillary acidic protein (GFAP) and factor VIII-related antigen (FVIII).

Background: Tumor proliferation in human intracranial meningiomas can be defined by the reactivity of the monoclonal antibody MIB-1 to the Ki-67 antigen. Vascular endothelial growth factor (VEGF), a pro-angiogenic factor, is a predictive marker for survival of dogs with intracranial meningiomas. Hypothesis: Ki-67 is expressed in canine intracranial meningiomas and is associated with VEGF expression. Ki-67 expression is a prognostic marker for patient outcome. Animals: Seventy client-owned dogs with WHO grade I intracranial meningiomas. Methods: Retrospective study assessing the degree of immunostaining for Ki-67 by MIB-1 and VEGF expression in intracranial meningioma tissue from dogs. MIB-1 Labeling Index (LI) was calculated with Image J NIH-software. Extent, intensity, and distribution of VEGF-expression was assessed semiquantitatively. Cross tabulations with Fisher's exact tests and nonparametric Spearman's rank correlations were performed to identify associations between VEGF expression and MIB-1 LI. Fifteen dogs underwent postsurgical radiotherapy and were included in survival analysis. The effect of MIB-1 LI on survival was examined by Kaplan-Meier and Cox proportional hazards regression procedures. Results: Ki-67 staining was positive in 91% (64/70) and VEGF expression was detected in 96% (67/70). There was no significant association between VEGF expression and MIB-1 LI. MIB-1 LI was not associated with survival. Conclusions and Clinical Importance: MIB-1 antibody can be used to document cell proliferation in intracranial meningiomas in dogs, but does not predict outcome. No association between VEGF as a marker of angiogenesis and tumor proliferation was found. Angiogenesis might be a more important predictor of meningioma activity in dogs than is Ki-67. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]