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Summary A 10-year-old entire male French bulldog was presented following clusters of generalized tonic–clonic epileptic seizures. Neurolocalization was consistent with a lesion in the left forebrain. Magnetic resonance imaging of the brain revealed a large, ill-defined, intra-axial, space-occupying lesion at the level of the left temporal and parietal lobes, causing marked compression of the adjacent parenchyma. Computed tomography of the thorax and abdomen was consistent with disseminated metastatic disease. The dog was humanely destroyed and subjected to necropsy examination. Histological examination of the brain revealed a metastasis of prostatic carcinoma within an anaplastic oligodendroglioma in the left forebrain. To the author's knowledge, this is the first report describing clinical, imaging and histopathological features of an intracranial tumour-to-tumour metastasis in the brain of a dog. Graphical abstract Tumour-to-tumour metastasis phenomenon in the brain of a dog, where a prostatic adenocarcinoma metastatizes within an anaplastic oligodendroglioma. An intratumoural mass resembling metastatic foci is present in the center of the oligodendroglial tumour. PanCK immunopositivity in the brain is observed, indicating their epithelial origin demonstrating this phenomenon. Image 1 [ABSTRACT FROM AUTHOR]

Summary Human gliomas are malignant brain tumours that carry a poor prognosis and are composed of a heterogeneous population of cells. There is a paucity of animal models available for study of these tumours and most have been created by genetic modification. Spontaneously arising canine gliomas may provide a model for the characterization of the human tumours. The present study shows that canine gliomas form a range of immunohistochemical patterns that are similar to those described for human gliomas. The in-vitro sphere assay was used to analyze the expansion and differentiation potential of glioma cells taken from the periphery and centre of canine tumours. Samples from the subventricular zone (SVZ) and contralateral parenchyma were used as positive and negative controls, respectively. The expansion potential for all of these samples was low and cells from only three cultures were expanded for six passages. These three cultures were derived from high-grade gliomas and the cells had been cryopreserved. Most of the cells obtained from the centre of the tumours formed spheres and were expanded, in contrast to samples taken from the periphery of the tumours. Spheres were also formed and expanded from two areas of apparently unaffected brain parenchyma. The neurogenic SVZ contralateral samples also contained progenitor proliferating cells, since all of them were expanded for three to five passages. Differentiation analysis showed that all cultured spheres were multipotential and able to differentiate towards both neurons and glial cells. Spontaneously arising canine gliomas might therefore constitute an animal model for further characterization of these tumours. [ABSTRACT FROM AUTHOR]

Summary: In veterinary medicine, the term peripheral nerve sheath tumour is usually restricted to neoplasms that are closely associated with an identified nerve. Thirty-three cases of canine cutaneous tumours previously classified as spindle cell tumours with features resembling peripheral nerve sheath tumours were examined. Two histological patterns were identified: dense areas of spindle shaped cells resembling the Antoni A pattern and less cellular areas with more pleomorphic cells resembling the Antoni B pattern. Immunohistochemically, all tumours uniformly expressed vimentin and 15/33 (45.4%) had scattered and patchy expression of S-100. Laminin expression was found in 25/33 (75.7%) tumours and collagen IV labelling occurred in 14/33 (42.4%). Expression of protein gene product 9.5 was detected in 31/33 (93.9%) of tumours and neuron specific enolase labelling was present in 27/33 (81.8%). Glial fibrillary acidic protein was only expressed within the cytoplasm of some large multinucleated cells in one tumour. These findings suggest that any cutaneous tumour with one of the two histopathological patterns described above should be described as a cutaneous peripheral nerve sheath tumour and that expression of S-100, laminin and collagen IV may be used to define a schwannoma. [Copyright &y& Elsevier]

Summary: This report describes the incidence, location and histopathological and immunohistochemical features of 30 canine meningiomas, of which 22 were intracranial, three were retrobulbar and five were located in the spinal canal. Nine types of meningioma were diagnosed: transitional (9), meningothelial (5), psammomatous (3), anaplastic (3), fibroblastic (2), angioblastic (2), papillary (2), microcystic (1) and meningiomas arising from the optic nerve (3). One of the optic nerve tumours had a granular cell component. All tumours were examined immunohistochemically with antibodies against vimentin, S100, neuron-specific enolase (NSE), cytokeratin (CK) and glial fibrillary acidic protein (GFAP). Vimentin was demonstrated in all tumours, and concentric whorls of cells showed more intense labelling than did bundles of fibroblastic cells. S100 labelling was detected in all tumours except a single angioblastic meningioma. The intensity of labelling for S100 was lower than that for vimentin, and bundles of fibroblastic cells showed particularly strong positivity. NSE labelling was highly variable, but most tumours displayed moderate positivity. CK expression was observed in five of the 30 meningiomas, and was stronger in areas of microcystic differentiation. Most of the tumours were GFAP-negative, but two fibroblastic meningiomas were strongly positive. [Copyright &y& Elsevier]

Highlights • Cyclooxygenase-2 (COX-2) expression in 15 feline meningiomas was assessed via immunohistochemistry. • All meningiomas displayed positive immunostaining. • The expression of COX-2 was not significantly correlated with WHO grade. • COX-2 expression was significantly associated with the presence of necrosis. Abstract Meningioma is the most common primary brain tumor in cats and occurs less frequently in the spinal cord. This study aimed to investigate cyclooxygenase-2 (COX-2) expression in feline meningiomas, and the possible association between COX-2 immunoreactivity and tumor grade using eight low-grade and seven high-grade meningiomas. All tumors (n = 15/15) were immunoreactive to COX-2. The expression of COX-2 was not significantly correlated with tumor grade (P = 0.22 and 0.34 for staining and intensity, respectively) but was significantly associated with necrosis (P = 0.04 and 0.01 for staining and intensity, respectively). The findings in this study suggest that feline meningiomas express COX-2, but there were no differences in COX-2 immunoreactivity patterns between low- and high-grade meningiomas. However, the association between COX-2 expression and the presence of necrosis indicates a potential area for therapeutic intervention with selective COX-2 inhibitors. [ABSTRACT FROM AUTHOR]

Granulomatous meningoencephalitis (GME) and necrotizing encephalitides (NE) are the most common immune-mediated inflammatory diseases of the central nervous system in dogs. Activation of the fibrinolytic system in multiple sclerosis, a similar immune-mediated disease affecting the central nervous system in humans, seems to be related to disease progression. The aim of this study was to identify fibrin/fibrinogen and D -dimer deposition, as well as presence of intravascular thrombosis (IVT) in brains of dogs with a diagnosis of GME or NE. Immunohistochemical studies using antibodies against fibrin/fibrinogen and D -dimers were performed. Statistical analyses were performed to determine whether there were differences in the presence and location of fibrin/fibrinogen, D -dimers deposits, and IVT between GME and NE. Samples from sixty-four dogs were included in the study: 32 with a diagnosis of GME and 32 with a diagnosis of NE. Fibrin/fibrinogen depositions were detected in all samples and d -dimers were detected in 43/64 samples. IVT was present in 29/64 samples, with a significantly higher score in samples from dogs with NE than in samples from dogs with GME (P = 0.001). These data support hemostatic system activation in both diseases, especially NE. This finding might be related to the origin of the necrotic lesions seen in NE, which could represent chronic ischemic lesions. Further studies are needed to investigate the association between vascular lesions and the histopathological differences between GME and NE and the hemostatic system as a potential therapeutic target. • Fibrin/fibrinogen was in all samples of meningoencephalitis of unknown origin. • In necrotizing encephalitides (NE) deposits were located mostly inside glial cells. • Intravascular thrombosis in NE could explain the origin of the necrotic lesions. • Presence of D -dimers indicated local activation of coagulation and fibrinolysis. [ABSTRACT FROM AUTHOR]