Intracranial medulloblastoma as the cause of progressive ataxia in a 6-month-old draft horse cross gelding.

We describe the unique clinical presentation of a central nervous system neoplasm in a 6-month-old draft horse cross gelding. Based on the neurologic examination at admission, neurolocalization was most consistent with a mildly asymmetric cervical, multifocal, or diffuse myelopathy. Mild vestibular involvement also was considered, but no cranial nerve deficits were observed. The gelding was negative for Sarcocystis neurona or Neospora hughesi based on paired serum and cerebrospinal fluid (CSF) samples analyzed, with no evidence of cervical compression based on contrast myelography. The horse was euthanized because of progression of clinical signs. At necropsy, a mass was identified associated with the cerebellum, and histopathology was consistent with medulloblastoma, which has not been reported previously in the horse.

Dysplastic gangliocytoma of the cerebellum in a cat.

A 2.5-year-old cat presented with progressive ataxia and lethargy. Magnetic resonance imaging (MRI) showed enlargement of the cerebellum and herniation of cerebellar vermis. Postmortem examination confirmed the MRI findings, and histopathology showed numerous large dysplastic neurons populating and displacing the Purkinje cell layer and extending into the molecular and granular layers of the cerebellum. The lesion was diagnosed as dysplastic gangliocytoma of the cerebellum. In humans, this tumor is often associated with Cowden syndrome, a genetic disorder characterized by multiple hamartomas and an increased risk of developing certain neoplasms, known to be linked to a germline mutation of the phosphatase and tensin homolog (PTEN) gene. Reduction in PTEN nuclear and cytoplasmic immunohistochemical labeling of dysplastic neurons in this case suggested a possible PTEN mutation involved in the tumorigenesis. This report provides a detailed pathology description of the tumor and the use of neuronal and PTEN markers which will help guide pathologists presented with this rare condition in the future.

A clinical case of presumed cerebellar medulloblastoma in a Japanese Black calf with increased neuron-specific enolase in cerebrospinal fluid.

A 2-day-old Japanese Black male calf that presented with opisthotonos with spastic extension of all four limbs and nystagmus was presented. Evaluation of cranial neurology revealed a horizontal slow nystagmus and absence of menace response in the left eye. Necropsy revealed a mass located between the posterior margin of the cerebrum and anterior margin of the cerebellum, and continuously with the cerebellar lesion. The brainstem was severely compressed by those lesions. Original structures of the cerebellum were mostly replaced by grayish-white and brownish tissues. Those lesions were diagnosed as presumed cerebellar medulloblastoma by histopathological and immunohistochemical examination. As neuron-specific enolase in the cerebrospinal fluid which is a biomarker for neuronal damage was increased compared with healthy calves.

Mature congenital intraneural teratoma in cerebellum of pig.

The biological behavior of teratomas depends on several interdependent clinical and epidemiological variables such as age at diagnosis, sex, tumor microenvironment, and tumor morphology, among others. All these variables are correlated to different cytogenetic and molecular aberrations (Harms et al., 2006). There are null reports of teratomas in pigs. The aim of this study was to characterize the tissues present in a mature congenital intraneural teratoma in the cerebellum area of a Landrace female pig of 6-7 weeks old. In this study, tissue control samples were used to validate each staining method. Sections from the teratoma showed normal histology of the cerebellum, including rounded Purkinje neurons with abundant cytoplasm, euchromatic nuclei, and prominent nucleoli; glial cells with a scarce amount of cytoplasm and small and highly basophile-nuclei (compact chromatin) and axonal tracts (white matter). Interestingly, we also observed areas with tissues different from the nervous tissue, including bundles of well-defined skeletal muscle fibers with a striated pattern and peripheral nuclei; hyaline cartilage plaques, with prominent presence of chondrocytes in their lagoons forming isogenous groups surrounded by a territorial and interterritorial matrix; trabeculated bone tissue; and adipocytes, which are ring-shaped cells with peripheral flattened nuclei, as a result of the presence of a central large lipid droplet. To our knowledge, this study is the first to describe a congenital intraneural mature teratoma in the cerebellum of a pig.

Central Nervous System B-cell Lymphoma in a Bald Eagle ( Haliaeetus leucocephalus).

An adult bald eagle ( Haliaeetus leucocephalus) presented for nystagmus and an inability to fly. On physical examination, the eagle was open-mouth breathing and tachycardic at 200 beats per minute, had a wrinkled cere and sunken eyes, and was an estimated 10% dehydrated. Additionally, the eagle was extremely weak, with neurologic abnormalities including bilateral proprioceptive deficits, nystagmus, and no pupillary light reflex in the left eye. Despite aggressive treatment, the eagle continued to decline rapidly and subsequently died. On histologic examination, diffuse and widespread infiltration of neoplastic lymphocytes was present in the brain, optic nerves, and pecten. Immunohistochemical PAX-5 labeling confirmed B-cell lymphoma confined to the eye and nervous system. Test results for select avian retroviruses, Marek's disease, West Nile virus, avian influenza viruses, and Mycoplasma were negative. To our knowledge, this is the first report of B-cell lymphoma in a bald eagle. Although rare, this condition is a differential diagnosis in cases of neurologic or ocular diseases in birds.

Imatinib mesylate plus hydroxyurea chemotherapy for cerebellar meningioma in a Belgian Malinois dog.

An 8-year-old intact male Belgian Malinois, weighing 37.2 kg, was referred for evaluation due to right side facial paresis, ataxia and a 2-month history of decreased cognitive ability. Physical and neurological examinations revealed mild depression, left-sided head tilt, right-sided facial paresis and ataxia. A well-demarcated, broad-based cerebellar mass and hyperostosis were found on CT imaging of the brain. Based on these CT findings, a cerebellar meningioma was strongly suspected. Hydroxyurea and prednisolone were administered; after 4 weeks, there was reduction in mass size as compared to initial CT results. However, the mass size was found to have grown 6 weeks after hydroxyurea treatment. We then prescribed a combination of imatinib mesylate and hydroxyurea. Two weeks following combination treatment, the mass size had reduced significantly. The mass continuously decreased in size until the patient died during anesthesia. Cerebellar transitional meningioma was confirmed by histopathologic examination. To the author's knowledge, this is the first reported case of imatinib mesylate plus hydroxyurea therapy for the treatment of meningioma in veterinary medicine.

Magnetic resonance imaging features of cerebellar vermis medulloblastoma in an adult canine patient.

A seven-year-old, not-castrated male, Airedale Terrier presented with a history of ataxia and intention tremor of the head of three-week duration. Neurologic examination demonstrated severe hypermetria, intention tremor of the head and a bilateral menace response deficit. Magnetic resonance imaging revealed a well demarcated cerebellar vermis mass, hypointense on T1-weighted images, hyperintense on T2-weighted images, with multiple small foci of high signal similar to that of CSF. Foci dispersed in the mass creating a speckled appearance. Homogeneous faint, wispy post-contrast enhancement of the mass was noted; as a result the tumor became isointense to gray matter and was not clearly evident in post contrast images. The histopathological diagnosis of the excised tumor was cerebellar medulloblastoma.

Spontaneous cerebellar primitive neuroectodermal tumor in a juvenile cynomolgus monkey (Macaca fascicularis).

A neoplastic mass compressing the left cerebellar hemisphere and hindbrain was observed at trimming in a 3½-year-old male cynomolgus monkey from a control dose group. Microscopically, the neoplastic mass was nonencapsulated, invasive, and showed two morphological patterns. The predominant area consisted of densely packed undifferentiated, polygonal to spindle cells arranged in vague sheets supported by a scant fibrovascular stroma. The other area was less cellular and composed of round neoplastic cells separated by eosinophilic fibrillar material. Immunohistochemical staining for vimentin, synaptophysin, glial fibrillary acidic protein, neuron-specific enolase, neurofilament, and S-100 confirmed the presence of primitive undifferentiated neuroectodermal cells and some cells with neuronal or glial differentiation. On the basis of histopathology and immunohistochemical findings, a diagnosis of cerebellar primitive neuroectodermal tumor with neuronal and glial differentiation was made. Primitive neuroectodermal tumors are rare in animals including nonhuman primates; this is the first published report in this species.

MRI features of gliomatosis cerebri in a dog.

The features of gliomatosis cerebri involving the brainstem and cerebellum in a 3-year-old dog are described. In magnetic resonance (MR) images, there was diffuse loss of the cerebellar folia and cerebellar gray and white matter contrast. Multiple illdefined T2-hyperintensities were present in the cerebellar parenchyma. A poorly defined, T2-hyperintense mass effect was present ventral to the pons and rostral medulla. No contrast enhancement was noted. Cerebrospinal fluid (CSF) was normal. Postmortem examination was consistent with gliomatosis cerebri, based on compatible histopathology and immunohistochemical findings. Although rare, gliomatosis cerebri should be included as a differential for diffuse infiltrative central nervous system (CNS) lesions.

Gliomatosis cerebelli in a Saint Bernard dog.

A 6-year-old, neutered male Saint Bernard dog was presented with a 1-month history of ataxia, hypermetria and head tilt. High-field magnetic resonance imaging revealed a mass in the cerebellar vermis. During necropsy examination, a cream-coloured irregular area was observed in the cerebellar white matter. Microscopically, the mass comprised a diffuse neoplastic proliferation of spindle cells with oval pleomorphic nuclei in the white and grey matter of the cerebellum and pons and in the subpial area. Neoplastic infiltration was not found in the cerebrum. Immunohistochemistry revealed that the neoplastic cells were positive for vimentin and partially positive for glial fibrillary acidic protein. Based on these findings, the neoplastic lesion was diagnosed as gliomatosis cerebelli, without involvement of the cerebrum.

Quadrigeminal arachnoid cysts in a kitten and a dog.

Two quadrigeminal arachnoid cysts with different pathogenesis are described in 2 different species. A 10-week-old male Persian kitten with a progressively decreasing level of consciousness died spontaneously. At necropsy, mild internal hydrocephalus, caudal cerebellar coning, and cerebellar herniation through the foramen magnum were associated with a congenital quadrigeminal arachnoid cyst compressing the rostral cerebellum and shifting the entire cerebellum caudally. In contrast, a possibly acquired quadrigeminal cyst was observed in a 2-year-old male neutered Yorkshire Terrier in association with necrotizing encephalitis. Quadrigeminal arachnoid cysts have been rarely reported in dogs and humans.

Cerebellar ependymal cyst in a dog.

An 11-week-old, male, Staffordshire Bull Terrier had a history of generalized ataxia and falling since birth. The neurologic findings suggested a localization in the cerebellum. Magnetic resonance imaging of the brain was performed. In all sequences the area of the cerebellum was almost replaced by fluid isointense to cerebrospinal fluid. A complete necropsy was performed after euthanasia. Histologically, the lesion was characterized by extensive loss of cerebellar tissue in both hemispheres and vermis. Toward the surface of the cerebellar defect, the cavity was confined by ruptured and folded membranes consisting of a layer of glial fibrillary acidic (GFAP)-positive glial cells covered multifocally by epithelial cells. Some of these cells bore apical cilia and were cytokeratin and GFAP negative, supporting their ependymal origin. The histopathologic features of our case are consistent with the diagnosis of an ependymal cyst. Its glial and ependymal nature as demonstrated by histopathologic and immunohistochemical examination differs from arachnoid cysts, which have also been reported in dogs. The origin of these cysts remains controversial, but it has been suggested that they develop during embryogenesis subsequent to sequestration of developing neuroectoderm. We speculate that the cyst could have been the result of a pre- or perinatal, possibly traumatic, insult because hemorrhage, and tissue destruction had occurred. To our knowledge, this is the first description of an ependymal cyst in the veterinary literature.

Low-grade glial tumor with features of astroblastoma in a dog.

A 12-year-old, neutered, male Belgian Malinois/Great Dane cross dog presented with a 5-month history of weakness and lack of endurance followed by acute onset of rear limb ataxia. At autopsy, a 9 x 16 mm, multilobular, firm, white to tan, expansile mass was found in the cerebellum. Mild dilatation of the lateral ventricles was also noted. Histologically, there was a well-demarcated glial neoplasm composed of medium-sized astrocytic elements that had homogeneous cytoplasm, sometimes with globular eosinophilic inclusions, irregular peripherally located nuclei with a single nucleolus, and short cytoplasmic processes. Prominent perivascular pseudorosettes with cellular processes in contact with blood vessels were present. Some blood vessels exhibited hyalinized walls. Mitotic figures were not observed. Immunohistochemically, neoplastic cells expressed glial fibrillary acidic protein and vimentin. These features are consistent with an astroblastoma. This is the first clinicopathologic correlation and detailed description of a low-grade glial tumor with features of astroblastoma in a dog.

[Case-report. Malignant nerve sheath tumor in a cow with symptoms of suspected BSE]. / Fallbericht: Maligner Nervenscheidentumor bei einer Kuh mit BSE-verdächtiger Symptomatik.

We report here on a 3 1/2-year-old mother cow with a malignant perineural tumour near the pontine angle of the cerebellum, but which first drew attention because of clinical signs of BSE. Neurological symptoms that manifested during the course of the disease included disturbances in behaviour, movement and aesthesia, as described by BRAUN et al. (2001) in cases of BSE. Inconsistent with a diagnosis of BSE were focal neurological disturbances (head held aslant to the right, tendency to fall to the right, right-sided facial weakness, left-sided nystagmus and ventral strabismus). Following euthanasia, magnetic resonance imaging (MRI) revealed a tumour in the cerebellopontine angle. Histological findings describe a malignant peripheral nerve tumour of the vagal nerve with rhabdoid differentiation (a so-called Triton tumour) with an intracranial and an extracranial part.

Magnetic resonance imaging findings of an intracranial medulloblastoma in a Polish Lowland Sheepdog.

Medullobastoma is an uncommon caudal fossa tumor. The imaging features of medullobastoma in the dog are poorly described. In this report, the magnetic resonance (MR) appearance of a cerebellar medullobastoma in a dog is described. The MR features were similar to medulloblastomas in adult humans, with the tumor arising laterally and extending to the surface of the cerebellar hemisphere. Correct localization of medulloblastoma may be difficult and it should be considered as a differential for both extra- and intra-axial caudal fossa masses.