Cytology of a mass on the meningeal surface of the left brain in a dog

Intradural extramedullary granular cell tumour in a cat

A 7-year-old domestic shorthair cat was evaluated for progressive paraparesis, inability to jump, a paralysed tail and inability to void the bladder. Neurologic examination was consistent with a L4-S3 localisation. Survey radiographs of the lumbar vertebral column revealed L4-L7 vertebral body remodelling. A pre-contrast T1-weighted hyperintense, diffusely enhancing intradural lesion extending from L4 to S1 vertebral bodies was detected by MRI. Large, mesenchymal, round-to-polygonal cells arranged in nests or sheets were found on histologic examination at post mortem. These cells were characterised by abundant intracytoplasmic PAS-positive, diastase-resistant granules and positive immunoexpression of vimentin, S-100, neuron-specific enolase and desmin. This is the first report of a spinal granular cell tumour in a cat.

Magnetic resonance imaging diagnosis of brain tumors in dogs

A great deal of information is now available regarding the range of magnetic resonance imaging (MRI) features of many primary and secondary brain tumors from dogs. In this review, these canine neoplasms are grouped into meningeal masses, ventricular masses, intra-axial enhancing lesions, intra-axial mildly to non-enhancing lesions, and multifocal lesions. For each of these patterns, the major and sporadic neoplastic differential diagnoses are provided, and guidance on how to rank differential diagnoses for each individual patient is presented. The implication of MRI features such as contrast-enhancement, signal intensities and location is discussed. However, the information garnered from MRI must be correlated with all available clinical information and with epidemiological data before creating a differential diagnosis.

Diagnostic immunohistochemistry of canine and feline intracalvarial tumors in the age of brain biopsies

The focus of immunohistochemistry as applied to nervous system tumors is in identifying the neoplasm present and evaluating margins between normal and neoplastic tissue. Although not always utilized by specialists in neuropathology, immunohistochemistry remains useful to resolve concerns about the differentiation and rate of tumor growth. The aims of this review are to discuss the utility of immunohistochemical reagents currently used in diagnosis of canine and feline intracalvarial tumors, to indicate the applicability of some tests currently used in human nervous system tumors for domestic species, and to evaluate a few less commonly used reagents. A panel of biomarkers is usually needed to confirm a diagnosis, with groups of reagents for leptomeningeal, intraparenchymal, and ventricular neoplasms. In the future, signature genetic alterations found among feline and canine brain tumors--as correlated prospectively with diagnosis, rate of enlargement, or response to treatment--may result in new immunohistochemical reagents to simplify the task of diagnosis. Prospective studies determining the type and proportion of stem cell marker expression on patient longevity are likely to be fruitful and suggest new therapies. Due to increased frequency of biopsy or partial resection of tumors from the living patient, biomarkers are needed to serve as accurate prognostic indicators and assist in determining the efficacy of developing therapeutic options in nervous system tumors of dogs and cats.

Atypical meningeal granular cell tumor in a dog

A 10-year-old, female spayed Chihuahua dog was presented to the Veterinary Teaching Hospital at the University of Georgia for evaluation of seizures, abnormal mentation, and cervical pain of 2 months duration. On magnetic resonance imaging, there was generalized thickening of the meninges overlying the left cerebral hemisphere and along the falx cerebri. Despite symptomatic treatment, the dog remained neurologically affected. Consequently, the owners elected euthanasia. On gross examination, the meninges covering the left cerebral hemisphere were severely thickened and firmly adhered to the calvaria. On transverse section, the white matter of the left cerebral hemisphere was swollen, enlarged, and extended across the midline with resultant compression of the right cerebral hemisphere. Cytologic evaluation of an impression smear of the thickened meninges showed numerous large, spindloid to polygonal cells with abundant, amphophilic, vacuolated cytoplasm, present either in clusters or in individual cells. Histopathologic evaluation of the meninges revealed a poorly circumscribed and infiltrative, moderately cellular neoplasm, composed of vacuolated, spindloid to polygonal cells with marked anisocytosis and anisokaryosis, arranged in sheets, and occasionally separated by thick bands of connective tissue. Immunohistochemistry for vimentin revealed diffuse cytoplasmic staining of the neoplastic cells. Although the periodic acid–Schiff reaction was negative, ultrastructural findings showed numerous vesicles that were empty or that contained membranous or electron-dense material. Based on gross, microscopic, immunohistochemical, and ultrastructural changes, the meningeal neoplasm was diagnosed as an atypical granular cell tumor.

Granular Cell Tumor in a Lumbar Spinal Nerve of a Dog

A 2-year-old Great Dane dog with a 2.5-week history of progressive paraparesis was presented to the Veterinary Medical Teaching Hospital at the University of Wisconsin-Madison. Neurologic examination revealed nonambulatory paraparesis with reduced to absent withdrawal hind-limb reflexes and lumbar pain. Magnetic resonance imaging and gross pathology confirmed a larger regional lumbar mass and a second smaller extradural mass within the spinal canal. The left lumbar mass was associated with extensive hemorrhage; dissection showed a dark-red, soft, well-circumscribed mass measuring 2 cm × 1.5 cm × 0.5 cm within the left fourth lumbar spinal nerve. Histopathological evaluation with immunohistochemistry revealed sheets of round to polygonal cells with diffuse granular cytoplasm demonstrating diastase-resistant periodic acid–Schiff reactivity and positive immunoexpression of S100 and neuron-specific enolase. The smaller extradural mass within the spinal canal exhibited similar morphology. Based on gross, histological, and immunohistochemical evidence, the masses were diagnosed as granular cell tumor.

Intracranial meningioma with polygonal granular cell appearance in a Chihuahua

A menigioma with polygonal granular cell proliferation in an 11-year and 8-month-old male Chihuahua is described. The tumor was observed under the dura matter of the right cerebrum. Microscopically, the tumor consisted of solid growth foci of small- or large- sized polygonal cells, with pale-stained nuclei, prominent nucleoli, and fine granular to foamy eosinophilic cytoplasm. Some of the proliferating cells contained variable amounts of cytoplasmic PAS-positive granules. Immunohistochemical analysis revealed that neoplastic cells were positive for vimentin and S-100 protein. Ultrastructurally, the neoplastic cells contained vesicular structures with a few small round-shaped bodies in the cytoplasm. We diagnosed the case as canine meningioma with granular cell appearance.

Characterization of uterine granular cell tumors in B6C3F1 mice: a histomorphologic, immunohistochemical, and ultrastructural study

The granular cell tumor is most often a benign neoplasm of uncertain origin. Four uterine granular cell tumors in control and treated female B6C3F1 mice were identified in chronic studies at the National Toxicology Program. Two tumors occurred in untreated control animals and 2 in treated animals receiving different compounds. Tissue sections were evaluated histologically and stained with hematoxylin and eosin, periodic acid-Schiff with diastase resistance, Masson's trichrome, toluidine blue, phosphotungstic acid-hematoxylin, and stained immunohistochemically with a panel of antibodies to muscle (desmin, alpha smooth muscle actin), neural (S-100, neuron specific enolase), epithelial (wide-spectrum cytokeratin), and macrophage (F4/80) markers. The main histomorphologic feature of tumor cells was the presence of abundant cytoplasmic eosinophilic granules that stained positive for periodic acid-Schiff with diastase resistance. Tumors varied in appearance and were comprised of sheets and nests of round to polygonal cells with distinct borders. Nuclei were hyperchromatic, pleomorphic, and centrally to eccentrically located and often contained single nucleoli. Occasional multinucleated giant cells were observed. Tumors were pale pink and homogeneous with trichrome stain and negative with toluidine blue. Three tumors had positive to weakly positive immunoreactivity for desmin, and 1 was positive for alpha smooth muscle actin. Expression of S-100, wide-spectrum cytokeratin, and neuron-specific enolase was negative for all tumors. Ultrastructurally, prominent electron-dense cytoplasmic granules were abundant and contained secondary lysosomes with heterogeneous lysosomal contents. The characteristics of these uterine granular cell tumors were suggestive of a myogenic origin.

Granular Cell Tumor in the Testis of a Rabbit: Cytologic, Histologic, Immunohistochemical, and Electron Microscopic Characterization

An adult pet rabbit ( Oryctolagus cuniculus) presented with a progressively enlarging left testicle. Because neoplasia was suspected, the testicle was removed. Pathologic evaluation (exfoliative cytology, histopathology, immunohistochemistry, electron microscopy) indicated that the tumor was an intratesticular granular cell tumor. Granular cell tumor has not been described in rabbits before and has not been described in the testes of animals or postnatal humans. Granular cell tumor should be included as a differential diagnosis of testicular tumors, particularly Leydig cell tumor, because of potential histologic similarities.