A sacro‐caudal spinal cord choroid plexus papilloma in a shar‐pei dog

A seven‐year‐old shar‐pei dog was referred because of severe lumbosacral pain and faecal incontinence of 20 days’ duration. Neurological examination was characterised by plegic tail, absence of perineal reflex, dilated anus, perineum and tail analgesia, and severe lumbosacral pain. The neurological clinical signs were suggestive of a selective lesion involving sacral and caudal spinal cord segments and/or related nerve roots. A magnetic resonance imaging of lumbosacral spine was performed and was suggestive of an intradural lesion. Primary or secondary neoplasia was considered as the most probable differential diagnosis. The dog was euthanased upon the owner's request. Histopathological examination confirmed the presence of an intradural‐extramedullary neoplastic tissue enveloping intradural tract of spinal nerve roots. On the basis of histological and immunohistochemical findings, a diagnosis of well‐differentiated choroid plexus papilloma was made. To the authors's knowledge, this is the first case of primary or metastatic spinal choroid plexus papilloma in dogs.     

Choroid plexus carcinoma cells in the cerebrospinal fluid of a Staffordshire Bull Terrier

An 11-year-old female intact Staffordshire Bull Terrier was referred to the Queen's Veterinary School Hospital at the University of Cambridge with sudden onset of episodic behavioral changes, a mammary mass, and papilledema in the right eye. On physical examination the dog appeared depressed and had a head tilt to the right with anisocoria. Using magnetic resonance imaging, a broad-based lesion that obliterated the fourth ventricle was detected in the right brainstem. There was no evidence of pulmonary metastasis. Cerebrospinal fluid (CSF) was then obtained; fluid analysis showed an increased cell count (165 cells/μL, reference interval 0-7 cells/μL) and total protein (0.30 g/L, reference value <0.25 g/L). Cytologic evaluation revealed a population of atypical epithelial cells arranged in cohesive rafts and characterized by moderate to occasionally marked anisocytosis and anisokaryosis. The appearance was highly suspicious of a malignant epithelial neoplasm. The dog was euthanized and on postmortem examination an asymmetrical nonencapsulated cerebellar mass was found within the choroid plexus of the fourth ventricle with local extension into the cerebellopontine angle. Histologic sections of the cerebellar mass contained arborizing papillary structures covered by a single layer of atypical epithelial cells that showed local infiltration into the adjacent neuropil. The diagnosis was choroid plexus carcinoma. The atypical epithelial cells were negative for pancytokeratin and strongly positive for vimentin. The finding of clusters of choroid plexus epithelial cells in the CSF demonstrates the value of utilizing a relatively noninvasive diagnostic technique for diagnosis of choroid plexus tumors.     

Choroid plexus papilloma in a dog surviving for 15 months after diagnosis with symptomatic therapy

A 4-year-old female French bulldog presented with a 6-month history of right-sided head tilt and acute onset ataxia. Magnetic resonance imaging (MRI) showed a large mass lesion at the cerebellomedullary pontine angle. The dog was able to stand and walk after beginning symptomatic therapy with prednisolone, acetazolamide and glycerin. Magnetic resonance imaging 10 months after the first examination indicated slight expansion of the tumor. The dog was able to walk with continuous symptomatic therapy for 15 months until death, although the head tilt persisted. On postmortem examination, the gross tumor was slightly larger than when seen on the second MRI scan and was histopathologically diagnosed as a choroid plexus papilloma.     

Microcystic meningioma of the fourth ventricle in a dog

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.     

A histologic and immunocytochemical study of choroid plexus tumors of the dog

Sixteen choroid plexus (CP) tumors in 12 male and four female adult dogs were analyzed microscopically. Tumors were in the lateral (six), third (six), and fourth (four) ventricles. The average age of the dogs was 6 years. Tumors were classified by the following criteria: 1) choroid plexus papilloma (CPP), which resembled normal choroid plexus and had low mitotic activity; 2) choroid plexus papilloma (CPP), which resembled normal choroid plexus and had low mitotic activity; 2) choroid plexus papilloma with atypical features (atypical CPP), which had increased cellular density, nuclear atypia, two to four mitoses per 40x microscopic field, necrosis, and infiltration of the brain parenchyma and/or leptomeninges; and 3) choroid plexus carcinoma (CPC), which had marked nuclear atypia, poorly formed papillae, greater than four mitoses per 40x microscopic field, abnormal mitotic figures, and/or extraneural metastasis. The 16 tumors were classified either as CPP or atypical CPP (none as CPC). Statistically significant associations between brain infiltration and necrosis and atypical CPP were identified. Immunohistochemical studies in 11 tumors demonstrated staining for keratin in three tumors, two of which also reacted with carcinoembryonic antigen (CEA). There was no immunoreactivity with glial fibrillary acidic protein or epithelial membrane antigen. Choroid plexus from one of three control dogs stained focally for cytokeratin only. It is concluded that normal choroid plexus and CP tumors in the dog express epithelial, but not glial differentiation.     

Psychomotor epilepsy associated with metastatic thymoma in a dog

A seven-year-old female German shepherd dog was presented with a history of anorexia, weight loss and fever of three months' duration. On general examination she showed a marked behavioural change represented by episodic excitement and 'fly snapping. A general blood screening showed neutrophilia with left shift and hyperalbuminaemia. Survey radiographs were taken and a mass was identified in the cranial mediastinum. Cytological examination of fine needle aspiration smears of the mass yielded a presumptive diagnosis of lymphoma. The dog was euthanased and necropsy findings concluded that the primary tumour was a thymoma; metastases were found in the choroid plexus, leptomeninges, cerebral cortex and hippocampus.     

Ureteral mast cell tumor in a dog

A 6-year-old, castrated male, mixed-breed dog was diagnosed with partial unilateral ureteral obstruction secondary to a ureteral mass. The ureteral mass was surgically resected, and an ureteroneocystostomy was performed. Histopathology of the ureteral mass was consistent with a poorly differentiated mast cell tumor (MCT). The patient recovered well but was euthanized 5 months postoperatively for central nervous system signs. A choroid plexus tumor was diagnosed during necropsy examination. There was no evidence of recurrence or dissemination of the ureteral MCT. Extracutaneous MCTs are rare in dogs, and primary MCT associated with the urinary tract has not previously been reported in the veterinary literature.     

Isolation of visna-maedi virus from the choroid plexus of an apparently healthy sheep in Italy

In this paper, the presence of visna-maedi in Italy, reported to exist since 1982 on clinical grounds, and the presence of anti-visna-maedi antibody is confirmed by the isolation of the viral agent from choroid plexus cells of an apparently healthy sheep. Gel diffusion test antigen, prepared from the explanted choroid plexus cells and from normal choroid plexus cells infected with the isolated agent, gave a positive reaction with one or two identity lines with reference antigens. The isolated agent gave both a characteristic cytopathic effect and a cytoplasmic fluorescence starting 24 hours after infection in normal choroid plexus cell cultures. Fluorescence was observed neither in control normal choroid plexus cells nor in infected normal choroid plexus cells incubated with a visna-maedi negative serum. By electron microscopy, budding forms arising from the cell membrane and extracellular particles of two distinct types were observed. One type was characterized by an electron-dense central core and a single membrane, and ranged from 80 to 110 nm, while the other had elongated bar-like cores and a double wall, and ranged from 100 to 140 nm. The characteristics observed for the isolated agent are identical to those reported by various authors for visna-maedi virus.     

Isolation of visna-maedi virus from the choroid plexus of an apparently healthy sheep in Italy

In this paper, the presence of visna-maedi in Italy, reported to exist since 1982 on clinical grounds, and the presence of anti-visna-maedi antibody is confirmed by the isolation of the viral agent from choroid plexus cells of an apparently healthy sheep.Gel diffusion test antigen, prepared from the explanted choroid plexus cells and from normal choroid plexus cells infected with the isolated agent, gave a positive reaction with one or two identity lines with reference antigens. The isolated agent gave both a characteristic cytopathic effect and a cytoplasmic fluorescence starting 24 hours after infection in normal choroid plexus cell cultures.Fluorescence was observed neither in control normal choroid plexus cells nor in infected normal choroid plexus cells incubated with a visna-maedi negative serum.By electron microscopy, budding forms arising from the cell membrane and extracellular particles of two distinct types were observed. One type was characterized by an electron-dense central core and a single membrane, and ranged from 80 to 110 nm, while the other had elongated bar-like cores and a double wall, and ranged from 100 to 140 nm. The characteristics observed for the isolated agent are identical to those reported by various authors for visna-maedi virus.     

Scanning electron microscopy of the choroid plexus of the lateral ventricle of the horse

The present study examined the ultrastructure of the choroid plexus of the lateral ventricle of the horse. The material was fixed in 2.5% glutaraldehyde in 0.1 m sodium phosphate buffer, pH 7.3, processed and analysed by scanning electron microscopy. The choroid plexus was characterized by regions with a predominance of villi, which resembled finger-like projections or bunches of grapes, and others where straight and uniform folds predominated. Epithelial cells projected into the ventricle and large amounts of cilia and microvilli were observed on their surface. The choroid glomus corresponded to a dilatation of the choroid plexus and was characterized by blood vessels of different calibres surrounded by connective tissue.     

Two cases of paradoxical vestibular syndrome in Rough Collies

Two cases of paradoxical vestibular syndrome are described. The principal clinical signs were a persistent head tilt to the right and a progressive ataxia in unrelated 6-year-old Rough Collies. In both dogs the primary lesion found post mortem was a papilloma of the choroid plexus of the fourth ventricle on the left side. This was associated with severe disruption of the cerebellar peduncles, cerebellar folia and the medulla oblongata adjacent to the tumour.     

IMAGING DIAGNOSIS: TRAUMATIC DURAL TEAR DIAGNOSED USING INTRATHECAL GADOPENTATE DIMEGLUMINE

A dog with traumatic monoplegia had a spinal cord lesion, identified using conventional magnetic resonance imaging. In addition, the intrathecal use of gadopentate dimeglumine allowed identification of two sites of cerebrospinal fluid leakage from the vertebral canal, supporting a diagnosis of brachial plexus avulsion.     

Central nervous system lesions caused by canine distemper virus in 4 vaccinated dogs

We examined the cerebellum and cerebrum of 4 vaccinated dogs, 3–60-mo-old, that displayed clinical signs of canine distemper virus (CDV) infection, and died 7–40 d after developing neurologic signs. The main histologic lesions were demyelination, gliosis, meningitis, perivascular lymphocytic cuffing, and inclusion bodies. These lesions were similar in all 4 cases regardless of the time since vaccination, except that meningoencephalitis and gliosis were subacute in 3 dogs and chronic in 1 dog. However, these differences did not appear to be related to their vaccination status. Immunohistologically, a CDV-positive immunoreaction was seen mainly in astrocytes, neurons and their axons, lymphocytes around and in the blood vessels of the pia mater and choroid plexus, ependymal cells of each ventricle, and the cells of the choroid plexus. The histologic and immunohistologic changes were similar in the cerebellum and cerebrum. The genetic characterization of the virus strains in 2 of these naturally occurring canine distemper cases confirmed that they were South American wild-type strains (Kiki and Uy251) belonging to the EU1/SA1 lineage. These strains are not included in the commercial CDV vaccines available in Uruguay.     

CHOROID PLEXUS CYST IN A DOG

A 6-year-old male Doberman Pinscher had a 2-month history of dysequilibrium. Lesion localization was determined to be the cerebellomedullary pontine angle. In computed tomographic images, a well-defined, circular, hypoattenuating mass was visible at the cerebellomedullary pontine angle. The lesion, which was isoattenuating to cerebrospinal fluid, was 4 x 8 mm in diameter. Peripheral ring enhancement was evident after contrast medium administration. A choroid plexus cyst was diagnosed histopathologically.     

Spontaneously occurring intracranial lipomatous hamartoma in a young BALB/c mouse and a literature review

An intracranial lipomatous hamartoma was found in the third ventricle of a 7-week-old female BALB/cAnNCrlCrlj mouse. The nodule was composed of mature white adipose cells, which contained one large fat droplet, and there was no evidence of cytological atypia. The brain parenchyma at the retrosplenial granular cortex and the hippocampus in the cerebrum were slightly compressed, and the choroid plexus was dislocated downward. Scattered capillary vessels penetrated the nodule from the surrounding tissue. Based on these findings, the lesion was diagnosed as a lipomatous hamartoma that occurred from the roof of the third ventricle. This extremely rare tumor-like nodule represents an overgrowth of the mature adipocyte population as a malformation rather than a true neoplasm.     

Sur la Microvascularisation des Plexus Choroïdes des Ventricules Latéraux chez la Chèvre (Capra hircus)

The goat choroid plexus angioarchitecture of the lateral ventricles was studied under the SEM using the method of “microvascular corrosion casts”. The whole plexus is semilunar shaped and directed in an antero-posterior, latero-median fashion. In the plexus the lateral extremity is larger than the median one. All the components of the vascular bed (arteries, venes and capillaries) of the choroid plexus have interesting morpho-structural features. In particular, the capillaries are more developed than the other components and they are variously located on both sides of the plexus. The capillary network has a various organization in different zones of each side of the plexus.     

Microarray analysis of differentially expressed genes of primary tumors in the canine central nervous system

The pathophysiologic similarities of many human and canine cancers support the role of the domestic dog as a model for brain tumor research. Here we report the construction of a custom canine brain-specific cDNA microarray and the analysis of gene expression patterns of several different types of canine brain tumor. The microarray contained 4000 clones from a canine brain specific cDNA library including 2161 clones that matched known genes or expressed sequence tags (ESTs) and 25 cancer-related genes. Our study included 16 brain tumors (seven meningiomas, five glial tumors, two ependymomas, and two choroid plexus papillomas) from a variety of different dog breeds. We identified several genes previously found to be differentially expressed in human brain tumors. This suggests that human and canine brain tumors share a common pathogenesis. In addition, we also found differentially expressed genes unique to either meningiomas or the glial tumors. This report represents the first global gene expression analysis of different types of canine brain tumors by cDNA microarrays and might aid in the identification of potential candidate genes involved in tumor formation and progression.