Papillary meningioma in the dog: a clinicopathological study of two cases

Meningioma with rhabdoid features: Pathologic findings in dogs

Rhabdoid meningioma is a rare type of meningeal neoplasm in humans. This study reports the clinical, pathological, and ultrastructural features of 4 cases of canine meningioma with rhabdoid features. The cases were female and 8 to 12 years of age. Biopsies from complete surgical resections were examined for all cases. The whole brain with tumor recurrence was collected at necropsy in 2 dogs. Histologically, the tumors consisted of discohesive sheets of oval-polygonal cells with abundant eosinophilic cytoplasm and occasional paranuclear hyaline-like inclusions. Cells were intensely immunopositive for vimentin, negative for melan A and S100 protein in all cases, and showed variable immunolabeling for cytokeratin in 2 cases. Focal glial fibrillary acidic protein (GFAP)-immunopositive cells were present in 1 case. Ultrastructurally, the rhabdoid cells in case 1 contained prominent cytoplasmic whorls of intermediate filaments, recapitulating the ultrastructural features of rhabdoid meningioma in humans. In cases 2 and 3, the meningioma cells contained interdigitating cell processes folded in a maze-like fashion resembling rhabdoid-like meningioma in humans. In case 4, the voluminous cytoplasm contained many round-to-flattened mitochondria admixed with rough endoplasmic reticulum, indicating a predominant oncocytic differentiation and not the rhabdoid differentiation suggested by light microscopy. Thus, rhabdoid morphology occurs in different types of meningiomas, and ultrastructural findings are essential for a correct diagnosis.

Meningioma microcístico com metástase pulmonar em canino: relato de caso

RESUMO Meningiomas são os principais tumores primários do sistema nervoso central (SNC) que afetam cães e gatos. Na maioria dos casos, são neoplasias benignas, geralmente expansivas, causando compressão do SNC, e raramente fazem metástase para outros órgãos. O presente trabalho tem como objetivo relatar a ocorrência de um meningioma microcístico com metástase pulmonar em um canino de 11 anos de idade, com sinais clínicos de andar cambaleante, compressão da cabeça contra objetos, agitação, salivação e agressividade. Na necropsia, foram observadas, no encéfalo, massas bem delimitadas pardo-avermelhadas, firmes, de aspecto granular, localizadas no córtex parietal e nos núcleos da base. Inúmeras micronodulações de aspecto semelhante foram observadas no pulmão. Histologicamente observaram-se nódulos formados por células neoplásicas fusiformes, com núcleos grandes e alongados e nucléolos evidentes, dispostas de forma frouxa, formando vacúolos e microcistos. À imuno-histoquímica, o meningioma apresentou marcação fortemente positiva para citoqueratina e negativa para vimentina. Por meio da histopatologia e da imuno-histoquímica, foi possível estabelecer a classificação histológica de meningioma microcístico, bem como diferenciá-lo de outras doenças que cursam com sinais nervosos.

A retrospective study of skull base neoplasia in 42 dogs

This study describes the prevalence and distribution of 42 cases of skull base neoplasia in dogs between 2000 and 2014. The average age of affected individuals was 9.5 years, and there was no sex or breed predisposition. The most common skull base neoplasms were meningioma (25 cases) and pituitary adenoma (9 cases). Less common tumors included craniopharyngioma (2 cases), nerve sheath tumor (2 cases), and 1 case each of pituitary carcinoma, meningeal oligodendrogliomatosis, presumed nasal or sinonasal carcinoma, and multilobular tumor of bone. All neoplasms caused some degree of compression of adjacent structures. The distribution of the tumors was greatest in the sellar region ( n = 18), followed by the paranasal region ( n = 12), caudal cranial fossa ( n = 10), central cranial fossa ( n = 1), and rostral cranial fossa ( n = 1).

What is your diagnosis? Intracranial mass in a dog

A 9-year-old, spayed female Chihuahua was presented for evaluation of acute, progressive neurologic disease. On physical examination the dog was depressed and laterally recumbent. The dog had marked neutrophilia with a toxic left shift and monocytosis. Using computed tomography with contrast enhancement a large intracranial mass lesion was identified in the rostral portion of the brain. The mass extended from the central thalamic region rostral to the cribiform plate and obliterated the lateral ventricles. A fine needle aspirate of the mass contained moderately pleomorphic polygonal cells with many intranuclear cytoplasmic pseudoinclusions (ICPs). The primary differential diagnosis was meningioma, based on cell morphology and the presence of ICPs. At necropsy, the mass was well-demarcated, unencapsulated, and densely cellular. Cells were arranged in papillary projections on fibrovascular stalks, and eosinophilic ICPs and nuclear folding were frequently seen. Cavitated areas of necrosis throughout the tumor mass were filled with intact and degenerated neutrophils. The histopathologic diagnosis was malignant papillary meningioma. ICPs are not frequently observed in Wright-stained cytologic preparations but may be found in many types of neoplasms, including meningiomas.

Histological and Immunohistochemical Study of 30 Cases of Canine Meningioma

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.

Diagnostic Correlation of CT-MRI and Histopathology in 10 Dogs with Brain Neoplasms

Ten dogs with primary (n = 8) and metastatic (n = 2) brain tumours were studied in an attempt to evaluate the diagnostic sensitivity of computed tomography (CT) or magnetic resonance imaging (MRI). Of the clinical signs noticed, seizures (seven of 10), behavioural abnormalities and cognition dysfunction (seven of 10), compulsive walking and circling (six of 10), sensorimotor (five of 10) and neuro-opthalmological (two of 10) dysfunction were the most common. In all 10 animals that finally died of the disease or were killed, the histopathological diagnosis that followed necropsy was taken as a golden standard in the CT or MRI prediction of the histological type of brain neoplasms. In every instance, tumour detection, morphology and histological differentiation were possible with the aid of either CT (seven of 10) or MRI (three of 10) imaging especially after contrast enhancement. Only one CT-evaluated dog, diagnosed as meningioma, was found to be astrocytoma on histopathology. Interestingly, a rare case of cerebellar medulloblastoma was correctly identified in MRI scans.

Cerebellopontine Angle Meningioma Expanding into the Sella Turcica in a Dog

A 10-year-old, female poodle was presented with left paresis and vestibular signs, following left enophthalmus and atrophy of the cheek. Magnetic resonance imaging revealed a mass along the base of the brain and extending from the left cerebellopontine angle to the sella turcica. The mass showed isointensity on the T1-weighted image and T2-weighted image, and was enhanced by contrast medium (Gd-DTPA). Although occipital craniotomy was carried out and the mass removed, the dog died without recovering from the anesthesia. The tumor was diagnosed pathologically as fibroblastic meningioma.