Canine eyelid granular cell tumor: a report of eight cases

To describe a previously unreported neoplasm of the medial canthus and eyelid in dogs. Clinical and pathologic features of granular cell tumors in the dog were reviewed. Granular cell tumors, arising from the medial canthal eyelid of eight dogs, were identified from the archives of the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). The affected dogs ranged in age from 5 to 12 years (mean of 9.25 years). Follow‐up information was available for seven of the eight cases. The clinical presentation included swollen hyperemic lids (4/8), ulcerated skin overlying the mass (2/8), and red conjunctiva (7/8). All eight of the cases had firm masses extending from the palpebral conjunctiva to the eyelid margin at the medial canthus. Histologically, the tissue was composed of a highly collagenous neoplastic growth. The neoplastic cells were oval to strap‐like cells with an oval bland appearing nucleus and abundant amounts of granular cytoplasm with very distinct cell boundaries. These granular cells were embedded in a dense collagen matrix. A PAS stain faintly highlighted the granular appearance of the neoplastic cells, which is a defining characteristic of this tumor. There was no recurrence in the seven cases available for follow‐up. Canine granular cell tumors of the medial canthus present clinically and histologically as a benign neoplasm. Granular cell tumors have a characteristic histological appearance. Granular cell tumors should be on the differential list for nodules of the medial canthus in dogs.     

Primary cardiac granular cell tumor in a dog

The histological, histochemical, and ultrastructural features of a granular cell tumor in the wall of the right atrium of the heart in a nine-year-old dog are described. The histologic appearance of the mass varied from areas of spindle-shaped cells to sheets of globoid cells with foamy granular cytoplasm. The globoid neoplastic cells contained numerous cytoplasmic granules which were variably positive to periodic acid-Schiff staining, with and without disastase digestion. Ultrastructurally, the globoid cells had numerous various-sized, heterogeneous lysosomes with pleomorphic content. A granular cell tumor originating in the heart has not been reported previously in animals. The support for a neural origin of these tumors by the recent identification of several nervous tissue specific proteins in their granular cells is discussed.     

Glioblastoma multiforme in three baboons (Papio spp)

Glioblastoma multiforme is the most malignant astrocytic neoplasm and the most common brain neoplasm of humans. Spontaneous neoplasms of the brain are rare in nonhuman primates. This report describes three glioblastomas in adult captive-reared baboons. The animals exhibited a range of clinical signs, including depression, weight loss, weakness, and blindness. All three neoplasms were located in the cerebrum, with extension into the pons in one case. Histologically, the tumors were similar and were characterized by cellular pleomorphism, multinucleated cells, areas of necrosis, microvascular proliferation (glomeruloid bodies), and palisading of neoplastic cells around blood vessels and areas of necrosis. Two baboons exhibited gemistocytic differentiation, and in one baboon, the neoplastic cells were predominantly spindle shaped with a fascicular growth pattern. Immunohistochemical staining for glial fibrillary acidic protein, vimentin, and S-100 protein was positive, whereas immunostaining for synaptophysin and chromogranin A was negative. Positive staining for the cell proliferation marker Ki67 ranged from 8.2% to 13.9%. Terminal deoxynucleotidyl transferase mediated dVTPnick end labeling (TUNEL) staining ranged from 1.8% to 5.7%. These baboon glioblastomas share many features with those of humans.     

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

An 11-year-old neutered male Labrador Retriever presented to Tufts University School of Veterinary Medicine for a 2-week history of seizures and altered behavior. Magnetic resonance imaging (MRI) revealed a homogeneously enhancing mass involving the surface of the left temporal, parietal, and occipital lobes of the brain, causing secondary hydrocephalus. Cytology samples obtained during rostrotentorial craniectomy contained abundant amorphous pink material suggestive of neuropil, scattered leukocytes, capillary fragments, large polyhedral nerve cell bodies, and other smaller cells with pale blue cytoplasm that occasionally were vacuolated and contained fine eosinophilic granules. The cytologic diagnosis was neoplasia, possibly meningioma. Ninety days after surgery the patient was euthanized after MRI results confirmed regrowth of the tumor. Histologic samples of the meningeal lesion collected at necropsy consisted of sheets and nests of loosely packed, large polygonal cells that compressed the brain parenchyma. The cytoplasm was eosinophilic and slightly granular, whereas nuclei were dense and eccentric. Neoplastic cells stained positive for S-100 protein, periodic acid-Schiff, and were partially diastase resistant. Vimentin staining was negative. Ubiquitin staining was light but diffusely positive. Ultrastructural features of the neoplastic cells included numerous secondary lysosomes and irregular pleomorphic nuclei. The final diagnosis was meningeal granular cell tumor. This case documents the cytologic and histologic features of an uncommon type of meningeal tumor.     

Immunohistochemical characterization of canine hyperplastic hepatic lesions and hepatocellular and biliary neoplasms with monoclonal antibody hepatocyte paraffin 1 and a monoclonal antibody to cytokeratin 7.

Immunostaining with monoclonal antibody (MoAb) hepatocyte paraffin 1 (Hep Par 1) and an MoAb to cytokeratin 7 (CK7) was performed on 105 formalin-fixed, paraffin-embedded canine hyperplastic and neoplastic hepatic lesions. Hep Par 1 was detected in 12/12 hyperplastic nodules, 17/17 hepatocellular adenomas, and 37/40 hepatocellular carcinomas. The staining was disseminated, granular, and cytoplasmic. This antibody did not react with normal or neoplastic biliary epithelium. Other hepatic tumors or tumors metastatic to the liver did not bind Hep Par 1 except one metastatic intestinal carcinoma. MoAb to CK 7 stained all hyperplastic biliary epithelium and benign cholangiocellular tumors (5/5) and 14/18 cholangiocellular carcinomas. One hepatocellular carcinoma had cells positive for both Hep Par 1 and CK 7. Liver was the only normal tissue tested that reacted with MoAb Hep Par 1. Only five nonhepatic tumors (one adrenocortical carcinoma, one interstitial cell tumor of the testis, one melanoma, and two salivary adenocarcinomas) of 277 tumors tested had focal/multifocal staining for Hep Par 1. Prolonged fixation did not alter the staining with Hep Par 1. We conclude that Hep Par 1 is a specific and sensitive marker for canine hepatocellular tumors and allows distinction between hepatocellular and biliary neoplasms.     

Rete testis mucinous adenocarcinoma in a dog

A bilateral testicular neoplasm from an 11-year-old mixed-breed male dog was removed surgically and examined histologically. The neoplasm was nonencapsulated and composed of acinar and tubular structures lined by one or more layers of neoplastic polyhedral epithelial cells with an abundant mucinous secretion. On histochemistry, all neoplastic cells and associated secretions were periodic acid-Schiff positive. Some neoplastic cells and all associated secretions were positive on mucicarmine stain, and some neoplastic cells, all the stroma, and associated secretions were positive on alcian blue stain. On immunohistochemistry, the neoplastic cells had strong diffuse cytoplasmic immunoreactivity for cytokeratin and vimentin, weak scattered cytoplasmic immunoreactivity for carcinoembryonic antigen and neuron-specific enolase, and no immunoreactivity for S-100. On the basis of histopathology, histochemistry, and immunohistochemical findings, a diagnosis of mucinous adenocarcinoma of rete testis was made. Rete testis adenocarcinoma is a well known but very rare neoplasm in humans. To our knowledge, this is the first report of the mucinous variant of adenocarcinoma of the rete testis in a dog.     

Lymphangiosarcoma with bone formation of the auricle in a dog

A 12-year-old mixed-breed neutered female dog was referred with cutaneous tumors at the left auricle. Histologically, the cutaneous tumor located in the dermis comprised numerous clefts and cavernous channels lined by neoplastic endothelial cells with no erythrocytes. Bone tissue without direct contact with neoplastic cells was seen in the well-developed stromal connective tissue. The neoplastic endothelial cells exhibited mild to moderate atypia. Immunohistochemically, neoplastic cells were positive for vimentin and negative for cytokeratin and factor VIII-related antigen. Basement membrane around the neoplastic lumens was positive for laminin in a linear or granular pattern. Ultrastructural examination revealed discontinuous basement membrane beneath the tumor cells. Histopathological features of this case were consistent with lymphangiosarcoma, and stromal ossification was characteristic.     

A mixed mesenchymal sarcoma in the soft palate of a dog: light and electron microscopic findings

Soft tissue tumors containing a mixture of neoplastic fibrous tissue, cartilage, and bone have previously been classified as extraskeletal osteosarcomas in the dog. These tumors are often poorly differentiated, contain multiple neoplastic cell types, and might be more appropriately called mixed mesenchymal sarcomas. The present neoplasm caused clinical signs of stridorous respiration and dysphagia in a four and one-half year old dog. Four neoplastic cell types were demonstrated by light and electron microscopy.     

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.     

Cutaneous rhabdoid tumor in a cat

Rhabdoid tumor is a highly aggressive neoplasm of unknown cellular origin in humans, usually occurring in the kidney and central nervous system of infants or children. In older patients, it occurs rarely in other organs, including the skin and soft tissues. A subcutaneous mass in a 13-year-old male mixed-breed cat was composed of nests or sheets of round to polygonal cells with glassy eosinophilic cytoplasmic inclusions. Immunohistochemically, many neoplastic cells expressed vimentin, localized to the cytoplasmic inclusions, whereas the cytoplasm of some neoplastic cells was diffusely positive for neuron-specific enolase, neurofilament, or S-100 protein. By electron microscopy, the cytoplasmic inclusions were found to be composed of aggregates of intermediate filaments. These findings are quite similar to the histologic, immunohistochemical, and ultrastructural features of human rhabdoid tumors and the few rhabdoid tumors reported in animals.     

Cytologic and histologic features of a poorly differentiated glioma in a dog

A 5-year old female Boxer with a 1-week history of progressive paresis and paraplegia had a T10-13 subarachnoid filling defect on myelography. Exploratory hemilaminectomy revealed an intramedullary spinal cord tumor which was subsequently diagnosed as a poorly differentiated glioma, most likely an anaplastic ependymoma. The cytologic, histologic, and immunocytochemical staining characteristics of this neoplasm are described. Differential diagnoses, including primary and secondary tumors involving the central nervous system are discussed.     

Extramedullary plasmacytoma in a horse with ptyalism and dysphagia.

A Clydesdale mare was examined for weight loss, inappetence, ptyalism, and dysphagia. The main abnormality revealed by serum biochemistry was a marked hyperglobulinemia, and protein electrophoresis revealed a monoclonal gammopathy in the gamma region. The urine was positive for Bence Jones proteins. These findings suggested a plasma cell tumor. The neoplasm could not be located with extensive antemortem examination. At postmortem, neoplastic cells morphologically compatible with plasma cells and positive for equine IgG with imunoperoxidase staining infiltrated the pericardium, mediastinal stromal tissues, adrenal glands, meninges, atrioventricular valves, aorta, abdominal and thoracic fat, and nerves, including the trigeminal nerve. The neoplastic cells invading the cranial nerves were responsible for many of the presenting signs.     

Dysgerminoma in an eastern rosella (Platycercus eximius eximius)

This report describes a case of dysgerminoma in a 21-year-old eastern rosella (Platycercus eximius eximius) that presented with dyspnea and a severely distended coelom. The bird was euthanatized, and a large, left-sided coelomic mass was identified. Microscopically, the mass was composed of sheets and nests of round to polygonal neoplastic cells with lacy cytoplasm. The neoplastic cells were weakly positive for vimentin and c-kit but negative for pancytokeratin, AE1, and inhibin. On the basis of the histomorphology and immunoreactivity, the neoplasm was determined to be a dysgerminoma. The variability of histologic appearance and immunohistochemical staining of dysgerminomas in humans compared with veterinary species is discussed.     

Cerebral granular cell tumor (myoblastoma) in a dog: case report and literature review.

An infiltrative granular cell tumor (myoblastoma) occurred in the superficial parieto-occipital cortex of an ataxic 12-year-old dog. The neoplasm was characterized by cells with numerous small PAS-positive, diastase-resistant cytoplasmic granules. The neoplasm also had numerous cells with large globular PAS-positive bodies (angulate bodies). Ultrastructurally, the neoplastic cells were characterized by numerous homogenous electron-dense, sharply bounded granules and large pleomorphic, indistinctly bounded granules. The angulate bodies were composed of 8- to 10-nm fibrils, a few of which formed parallel arrays or tubule-like structures. This represents the first report of a granular cell tumor in the central nervous system of the dog.     

A carcinoid tumor in the gallbladder of a dog

A cholecystectomy was performed on a 10-year-old spayed female mixed-breed dog with chronic weight loss, persistently increased liver enzyme activities, and cholecystomegaly identified by ultrasonographic examination. A subsequent diagnosis of a biliary carcinoid was made based on a neuroendocrine-type histologic pattern, cytoplasmic argyrophilia by Grimelius staining, immunopositivity for chromogranin A, and the ultrastructural finding of cytoplasmic secretory granules in neoplastic cells. Extrahepatic biliary carcinoid tumors are rare tumors of humans and have not been documented in domestic animals.     

Small intestine large granular lymphoma in a horse

A 12-year-old Appaloosa gelding was referred to the Texas Veterinary Medical Center with a history of chronic diarrhea and weight loss. At necropsy, numerous oval, craterlike ulcers were observed throughout the small intestine. Histologically, these lesions were composed of a neoplastic proliferation of round cells with intracytoplasmic phosphotungstic acid-hematoxylin-positive granules. The tumor cells stained positively for the CD3 antigen and negatively for a B-cell marker. A diagnosis of large granular lymphoma was based on the morphologic and immunohistochemical characteristics of the neoplasm. The postmortem presentation of this case depicted unusual multifocal, ulcerative lymphomatous lesions throughout the small intestine without involvement of the regional lymph nodes. The histologic and ultrastructural morphology of the neoplastic lymphocytes was similar to that in previously reported cases of abdominal equine large granular lymphomas, but in this case the neoplasm was restricted to the small intestine.     

Surgical removal of a choroid plexus oncocytoma in an adult cat

An 11‐year‐old male castrated domestic shorthair cat presented with left central vestibular dysfunction. Magnetic resonance imaging of the brain revealed a large, extra‐parenchymal, strongly contrast‐enhancing mass at the level of the left cerebellopontine angle and compressing the cerebellum and brainstem. The mass was surgically excised via left rostral and sub‐tentorial craniectomies and histopathology revealed an epithelial neoplasm composed of anastomosing cords of neoplastic cells that contained large amounts of finely granular hypereosinophilic cytoplasm and round nuclei. The cytoplasmic granules were variably positive with periodic acid‐Schiff and modified Gomori trichrome. Immunohistochemical staining with anti‐cytokeratin AE1/AE3 was diffusely positive. Electron microscopy revealed neoplastic cells that were full of electron‐dense organelles consistent with mitochondria. This is the first case of a choroid plexus oncocytoma in the central nervous system of any domestic animal species and highlights the role of successful surgical intervention in extra‐parenchymal neoplasia in the central nervous system.     

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.     

Papillary renal adenoma of distal nephron differentiation in a horse

A 20-year-old thoroughbred mare had a mass in the right kidney. The mass was encapsulated with fibrous capsule and composed of variably-sized papillary projections lined by a single layer of flattened to cuboidal neoplastic epithelial cells with no cytological and nuclear atypia. Immunohistochemically, the neoplastic cells were broadly positive for cytokeratin AE1/AE3 and granular staining for alpha-1-antitrypsin was focally detected; this immunohistochemical property was similar to that of the normal distal nephron. From these results, this case was diagnosed as papillary renal adenoma of distal nephron differentiation.