Pilocytic astrocytoma in a cat

A 12-year-old crossbred female cat was presented for necropsy with a history of anorexia, ataxia, convulsions, and blindness. Grossly, a whitish, firm, and well-circumscribed nodule with an irregular surface of approximately 1.5 cm in diameter was observed in the right dorsal, parietal, and occipital lobes of the brain. Histologically, the tumor was composed of neoplastic astrocytes forming irregular interweaving sheets and bundles. These cells were elongated, spindle-shaped, and bipolar, and some had clear cytoplasm and a dense nuclear chromatin pattern. Extensive areas of cartilaginous and osseous metaplasia were observed. By immunohistochemistry, the neoplastic cells were found to be markedly positive for S-100 protein and glial fibrillary acidic protein. On the basis of morphologic and immunohistochemical features, the diagnosis of pilocytic astrocytoma was made.     

Spinal cord astrocytoma in a cat

A nine-year-old neutered male domestic shorthaired cat with a history of spinal pain and progressive hindlimb dysfunction was presented to the Norwegian School of Veterinary Science. Following neurological and myelographic examination, an intramedullary mass affecting several lumbar spinal cord segments was diagnosed. A neoplastic lesion was suspected and a poor prognosis was given. On postmortem examination, the spinal cord was found to be dorsally flattened from the 12th thoracic vertebra to the fifth lumbar vertebra and severely thickened with a dorsal cleft from the fifth to the seventh lumbar vertebra. Histologically, the tumour was diagnosed as an anaplastic astrocytoma.     

A subependymal giant cell astrocytoma in a cat

A 6-year-old spayed female Domestic Shorthair cat presented with a 1 to 2-month history of blindness and altered behavior. At necropsy, a 1-cm-diameter, firm white mass was found arising from the subependymal region of the right lateral ventricular wall that protruded into and partially filled the lumen. Histologically, there was a well-demarcated, expansile paraventricular neoplasm composed of moderately pleomorphic cells within a richly fibrillar matrix arranged in interlacing streams and perivascular pseudorosette-like patterns. Neoplastic cells varied in morphology from small spindloid cells to larger polygonal cells with eccentric vesicular nuclei to neuronlike cells with vesicular nuclei and prominent nucleoli. The mitotic index was low. Immunohistochemically, neoplastic cells were positive for S-100 protein, glial fibrillary acidic protein, and neuron-specific enolase and negative for neurofilament protein. Ultrastructurally, the cells contained few to abundant bundles of intermediate filaments with variable numbers of mitochondria, endoplasmic reticulum, and ribosomes. These features are characteristic of subependymal giant cell astrocytoma (SEGA) in humans. To our knowledge, this is the first reported case of SEGA in domestic animals.     

Cerebral coenurosis in a cat

Coenurus serialis, the intermediate stage of Taenia serialis, was the cause of progressive, fatal, intracranial disease in a 5-year-old cat. X-Ray computed tomographic findings were identical to those associated with intracranial parasitic cysts in people, in whom x-ray computed tomographic features are considered pathognomonic and superior to those of other diagnostic methods. The presumed source of the coenurus was the owner's dog.     

Cerebral cysticercosis in a cat

The metacestode of Taenia solium, Cysticercus cellulosae, was recovered from the brain of a cat showing central nervous clinical signs ante mortem. This is the first record of cerebral cysticercosis in a cat in South Africa.     

Cerebral blastomycosis in a cat

A nine year old domestic shorthair cat was presented to the Small Animal Clinic, Ontario Veterinary College, with anorexia, depression and blindness. The animal died despite treatment. At necropsy, a space occupying mass was located in the left cerebral hemisphere. Histopathologically, the mass consisted of large numbers of fungal yeast-phase cells with an associated pyogranulomatous inflammatory response. The organisms were identified as Blastomyces dermatitidis on the basis of morphology and staining characteristics.

The purpose of this article is to describe the lesions of blastomycosis in the brain of a cat.

     

Cerebral Blastomyces dermatitidis infection in a cat

CASE DESCRIPTION: An 8-year-old domestic shorthair cat was evaluated because of signs of depression, circling, and visual deficits. CLINICAL FINDINGS: The cat had no cutaneous lesions, and results of an ophthalmologic examination and thoracic radiography were within reference limits. Computed tomography of the brain revealed a mass lesion involving the right parietal, temporal, and occipital lobes; the mass was in broad-based contact with the skull and smoothly marginated and had strong homogenous enhancement after contrast agent administration. During craniectomy, samples of the mass were collected for cytologic and histopathologic evaluations and microbial culture. A diagnosis of Blastomyces dermatitidis-associated meningoencephalitis with secondary pyogranulomatous inflammation was made. TREATMENT AND OUTCOME: Amphotericin B (0.25 mg/kg [0.11 mg/lb], IV) was administered on alternate days (cumulative dose, 1.75 mg/kg [0.8 mg/lb]). To minimize the risk of nephrotoxicosis, assessments of serum biochemical variables (urea nitrogen and creatinine concentrations) and urinalyses were performed at intervals. The third dose of amphotericin B was postponed 48 hours because the cat became azotemic. The cat subsequently received fluconazole (10 mg/kg [4.5 mg/lb], PO, q 12 h) for 5.5 months. Six months after discontinuation of that treatment, the cat appeared healthy and had no signs of relapse. CLINICAL RELEVANCE: Brain infection with B dermatitidis is typically associated with widespread disseminated disease. The cat of this report had no evidence of systemic disease. Blastomycosis of the CNS should be considered as a differential diagnosis for brain lesions in cats from areas in which B dermatitidis is endemic.     

Cerebral vascular hamartoma in a geriatric cat

An 11-year-old castrated male domestic medium hair cat was presented with neurological signs consistent with a right thalamocortical lesion. Computed tomography (CT) images revealed a heterogeneously, hyperattenuating, poorly contrast enhancing intra-axial mass within the right lateral ventricle. The histological diagnosis at post-mortem examination was vascular hamartoma with hemorrhage and necrosis. This is the first report of a vascular hamartoma affecting the thalamocortex in a geriatric cat. Also, this is the first time that CT images of a feline cerebral vascular hamartoma have been reported.     

Myelofibrosis in a cat (abstract)

A 2-year-old female domestic shorthair cat was presented with ill-health and marked ascites. Clinically, there was marked pallor of mucous membranes. Two haematological examinations and transudate-exudate analyses of peritoneal fluid were conducted 1 week apart, as well as a coagulation screen and routine serum biochemistry. The haematological examinations revealed a severe persistent non-regenerative anaemia. There were no abnormalities within the neutrophil and lymphocyte cell lines. Very occasional nucleated red blood cells (RBCs) in peripheral circulation and some RBC agglutination were seen. Analysis of peritoneal fluid disclosed a modified transudate, and small numbers of erythroid and myeloid precursors were observed on the second occasion. The cat was FIV/FeLV-negative, and there were no coagulation abnormalities. Following necropsy and histopathological examination, myelofibrosis and extramedullary haematopoiesis were seen. Thoracic masses were hyperplastic lymph nodes in which there was evidence of extramedullary haematopoiesis. The exact cause of the myelofibrosis was not obvious but it may have been a case of myeloid metaplasia, however not all the characteristics of this entity were present.     

An anaplastic astrocytoma (optic chiasmatic-hypothalamic glioma) in a dog

A tumor located in the optic nerve extended through the optic chiasm, involving the hypophysis and the hypothalamic area in a 3.5-year-old male Boxer dog. It showed a biphasic pattern in which numerous highly fibrillated, well-differentiated pilocytic areas were intermingled with pleomorphic, microcystic tumor tissue. Immunohistochemical analysis of the tumor revealed that most of the neoplastic cells were immunoreactive for S-100 protein, with less intensity for glial fibrillary acidic protein (GFAP) and vimentin. A diagnosis of anaplastic astrocytoma was made on the basis of the histopathologic findings and immunohistochemical results. Moreover, there were similarities with the malignant variant of pilocytic astrocytoma described in human adults as an optic chiasmatic-hypothalamic glioma.     

Disseminated mycobacteriosis in a cat (abstract)

A 12-year-old, FIV-positive domestic cat from rural Northland presented with diffuse and slowly progressive swellings of the vulva, tail base, head, and distal limbs. Fine needle aspirate biopsy of the subcutis revealed large numbers of pleomorphic acid fast bacteria. At necropsy, the dermis and subcutis in the affected areas were expanded by a pale yellow opaque infiltrate. Large ulcerated cutaneous swellings were present in the left maxillary area and bilaterally at the point of the jaw corresponding to the submandibular lymph nodes. Cutaneous nodules were present in the pre-auricular area. The skin of the carpi and tarsi was thickened and there was extensive hair loss, also evident over the tail base. The internal organs were normal in appearance. Histopathologically, the cutaneous swellings consisted of sheets of large foamy macrophages, macrophages, containing yellow/brown pigment and large numbers of acid-fast bacilli, that extended from the superficial dermis to the subcutis and fascia. Infiltrates of acid fast-laden macrophages were present in the liver, lung, spleen, and lymph nodes. Infection by a novel saprophytic Mycobacterium spp was considered most likely.