Ependymoblastoma in a dairy calf

Case report: Infratentorial Embryonal Tumor with Abundant Neuropil and True Rosettes (ETANTR) in an 8-month-old Maine Coon

An 8-month-old female Main Coon with a history of recurrent behavioral changes and anorexia was presented with sternal recumbency and depression. Within 5 days, the cat progressively worsened with symptoms of stupor and coma and was euthanized. At post-mortem examination, a solid, grayish infratentorial mass located in the midline rostrally to the cerebellum, was observed. Histologically, highly cellular clusters of small-to-medium undifferentiated cells were intermingled with paucicellular areas with fibrillary eosinophilic (neuropil-like) appearance. Numerous multilayered (ependymoblastic) true rosettes were present. The mitotic activity was frequent (up to 15 mitoses/HPF), involving both undifferentiated cells and rosettes. By immunohistochemistry (IHC), tumor cells were diffusely positive for vimentin, variably for synaptophysin, S-100, and NSE, and focally for NeuN; they were negative for GFAP and CK AE1/AE3. The histological and IHC aspects were consistent with an Embryonal Tumor with Abundant Neuropil and True Rosettes (ETANTR). Embryonal neoplasms of the central nervous system (CNS) are characterized by primitive undifferentiated cells, able to develop toward neuronal, glial, ependymal, and mesenchymal lines. Although extremely rare, juvenile embryonal tumors should be considered in the differentials of CNS disorders in young cats.

Clinical and magnetic resonance imaging findings of a cerebellar medulloblastoma in a heifer

Reports of medulloblastoma in cattle are scarce; however, this neoplasm should be included as a differential diagnosis in cases of cerebellar or central vestibular signs in young cattle. The MRI appearance of the medulloblastoma reported here, previously unreported in cattle, consisted of a T1-weighted hypointense and T2-weighted heterogeneously hyperintense intra-axial mass.

Meeting report: Spontaneous lesions and diseases in wild, captive-bred, and zoo-housed nonhuman primates and in nonhuman primate species used in drug safety studies

The combination of loss of habitat, human population encroachment, and increased demand of select nonhuman primates for biomedical research has significantly affected populations. There remains a need for knowledge and expertise in understanding background findings as related to the age, source, strain, and disease status of nonhuman primates. In particular, for safety/biomedical studies, a broader understanding and documentation of lesions would help clarify background from drug-related findings. A workshop and a minisymposium on spontaneous lesions and diseases in nonhuman primates were sponsored by the concurrent Annual Meetings of the American College of Veterinary Pathologists and the American Society for Veterinary Clinical Pathology held December 3-4, 2011, in Nashville, Tennessee. The first session had presentations from Drs Lowenstine and Montali, pathologists with extensive experience in wild and zoo populations of nonhuman primates, which was followed by presentations of 20 unique case reports of rare or newly observed spontaneous lesions in nonhuman primates (see online files for access to digital whole-slide images corresponding to each case report at http://www.scanscope.com/ACVP%20Slide%20Seminars/2011/Primate%20Pathology/view.apml). The minisymposium was composed of 5 nonhuman-primate researchers (Drs Bradley, Cline, Sasseville, Miller, Hutto) who concentrated on background and spontaneous lesions in nonhuman primates used in drug safety studies. Cynomolgus and rhesus macaques were emphasized, with some material presented on common marmosets. Congenital, acquired, inflammatory, and neoplastic changes were highlighed with a focus on clinical, macroscopic, and histopathologic findings that could confound the interpretation of drug safety studies.

Ventricular and Extraventricular Ependymal Tumors in 18 Cats

Ependymal tumors are reported rarely in domestic animals. The aims of this study were to examine the clinical and pathologic features of ventricular and extraventricular ependymomas and subependymomas in 18 domestic cats examined between 1978 and 2011. Parameters examined included age, sex, breed, clinical signs, and macroscopic and histopathologic features. The mean age of affected cats was 9 years, 4 months; median age, 8.5 years. There were 8 female and 4 male cats, and 6 cats for which sex was not recorded. Breeds included 10 domestic shorthaired, 2 domestic longhaired, 1 Persian, and 1 Siamese. Clinical signs included altered mentation or behavior, seizures, circling, propulsive gait, generalized discomfort, and loss of condition. The tumors often formed intraventricular masses and usually arose from the lining of the lateral or third ventricles, followed by the fourth ventricle, mesencephalic aqueduct, and spinal cord central canal. Three tumors were extraventricular, forming masses within the cerebrum and adjacent subarachnoid space. Histologically, 15 tumors were classified as variants of ependymomas (classic, papillary, tanycytic, or clear cell) and 3 as subependymomas. Tumors were generally well demarcated; however, 6 ependymomas focally or extensively infiltrated the adjacent neural parenchyma. Characteristic perivascular pseudorosettes were observed in all ependymomas; true rosettes were less common. Some tumors had areas of necrosis, mineralization, cholesterol clefts, and/or hemorrhage. This cohort study of feline ependymal tumors includes subependymoma and primary extraventricular ependymoma, variants not previously described in the veterinary literature but well recognized in humans.

Ependymoblastoma in a Japanese Black heifer

An 18-month-old, Japanese Black heifer had ananastasia over a two-week period. The heifer was euthanized and necropsied. Grossly, a brown and soft mass was found in the left cerebellar hemisphere, which originated from the fourth ventricle in the pons. Multiple papillary masses were also found on the wall of the fourth ventricle. There was massive dilatation of the cerebral aqueduct, and also in the third and lateral ventricles. Histologically, the neoplastic cells formed numerous ependymoblastic rosettes and perivascular pseudorosettes. In the fourth ventricle, the normal ependymal cells were replaced by papillary proliferation of the neoplastic cells. Ultrastructually, the neoplastic cells had a feature differentiating to the ependymal cell showing a few basal bodies in the cytoplasm and connecting to adjacent cells with junctional complexes. We diagnosed the present case as ependymoblastoma with its origins in the fourth ventricle.

Central primitive neuroectodermal tumour with ependymal differentiation in a dog

A central primitive neuroectodermal tumour (PNET) with ependymal differentiation was identified in an 18-month-old female Australian terrier dog that died following signs of central nervous system disease. A large space-occupying haemorrhagic mass replaced the thalamus and part of the hypothalamus of the brain. Microscopical examination revealed a tumour formed by a compact sheet of small cells that contained ependymal and perivascular pseudorosettes. Immunohistochemically, the neoplastic cells variably expressed glial fibrillary acidic protein, neuron-specific enolase, vimentin and cytokeratin, consistent with divergent differentiation of the tumour. This case is thought to represent the first description of PNET with ependymal differentiation in a dog.

Choroid Plexus Papilloma in a Scottish Highland Cow

Choroid plexus papilloma, a rare tumour in bovids, arising from the roof of the third ventricle was diagnosed at necropsy in a 4-year-old Scottish Highland cow. The animal presented with a 2-month history of progressive ataxia, ventromedial strabismus, and hyperaesthesia. Neoplastic epithelial cells were positive immunohistochemically for pancytokeratin and S-100, and negative for GFAP. Ultrastructurally, epithelial cells were characterized by intercellular junctions, zonulae adherens, and zonulae occludens. Neither cilia nor basal bodies were identified. The gross, microscopical, immunohistochemical and ultrastructural findings were consistent with those of a choroid plexus papilloma.

Tumours in calves: comparative aspects

In this paper, calf neoplasia is discussed in relation to a series of cases comprising (1). spontaneous congenital bovine tumours of fetuses and newborn animals, (2). spontaneous juvenile-type tumours in calves aged 2-12 months, and (3). iatrogenic tumours of calves. The congenital cases (n=14) consisted of tumours of a predominantly mesenchymal and malignant nature (malignant lymphoma, mesothelioma and mixed mesodermal tumour). In the juvenile cases (n=11), malignant lymphoma and sarcoma were the commonest forms. In comparing tumour patterns in calves with those reported in adult cattle, it was apparent that tumours were less common in the former (6 versus 60 per 100000) and that, with the exception of malignant lymphoma, the types of tumour differed. Carcinomas, which were virtually absent in calves, predominated in adults, probably due to the longer exposure of older animals to carcinogenic factors. In comparing tumour patterns in calves with those reported in pigs and children, it was clear that calf cases were mainly sporadic, with the notable exception of malignant lymphoma in twins. In young pigs, however, several types of tumour (some hereditary) were reported on a single farm as multiple cases. In children, tumours occurred more frequently than in calves, and many neoplasms in both children and calves could be regarded as embryonic tumours or hamartomas. Little is known about the pathogenetic pathways of tumours in calves, with the exception of congenital neuro-fibromatosis (hereditary) and possibly of mesotheliomatosis (due to asbestos). Modern methods of analysing chromosomal and gene aberrations may be helpful in clarifying the pathogenesis of congenital tumours.

Histopathological and immunohistochemical studies of intracranial nervous-system tumours in four cattle

Intracranial nervous-system tumours were diagnosed in three of 1092 bovine necropsy specimens submitted to the Department of Veterinary Pathology, Obihiro University between April 1983 and March 1996. A fourth case was a referral from the Department of Veterinary Pathology, Rakuno Gakuen University. Histopathological examination revealed four types of tumour: intracranial malignant peripheral nerve sheath tumour (MPNST), choroid plexus papilloma, differentiated fibrillary astrocytoma and anaplastic (malignant) astrocytoma. Immunohistochemically, the intracranial MPNST was strongly positive for S-100 protein and vimentin, and in places weakly positive for glial fibrillary acid protein (GFAP). The choroid plexus papilloma was strongly positive for epithelial membrane antigen (EMA), keratin, S-100 protein and vimentin, and positive for GFAP in places. The cytoplasm and fibrous component in the differentiated fibrillary astrocytoma were strongly positive for S-100 protein and GFAP. The anaplastic (malignant) astrocytoma was strongly positive for vimentin, S-100 protein and keratin in the cytoplasm and fibrous processes, and weakly positive for GFAP and EMA in places. Myelin basic protein (MBP) and synaptophysin showed a weak positive reaction in the marginal areas of the tumour.

Multicentric schwannomas causing chronic ruminal tympany and forelimb paresis in a Holstein cow

A nine-year-old Holstein cow that developed recurrent ruminal tympany and an abnormal forelimb gait and posture ultimately became recumbent and unable to rise, and was euthanased. A postmortem examination demonstrated numerous schwannomas affecting peripheral nerves and several thoracic and abdominal viscera.