Spontaneous complex pheochromocytoma in a Fischer 344 rat

A spontaneous complex pheochromocytoma was diagnosed in the adrenal gland of an aged female Fischer 344 rat. This expansile neoplasm consisted of pheochromocytoma and areas of ganglioneuroma. The supporting stroma of both neoplastic components contained spindle-shaped cells, which also formed large fascicles. Immunohistochemically, pheochromocytoma cells stained for synaptophysin and chromogranin, scattered ganglioneuroma cells stained for neurofilament protein, and the spindle-shaped stromal cells were positive for S-100 protein. Special stains demonstrated Nissl substance in the ganglioneuroma cells and nerve fibers in the fascicles.     

Bovine pheochromocytoma: case report and review of literature.

A pheochromocytoma had partially replaced the left adrenal gland of a mature, grade Hereford cow and had penetrated the caval wall with resultant production of an intravascular nodule having a diameter of 2 cm. A few small neoplastic emboli were in thin-walled capsular and trabecular blood vessels. Metastasis to other tissues was not demonstrated.     

Cerebral high-grade astrocytoma (glioblastoma) in a cat

A cerebral tumour was found in the right frontal lobe of a 7-year-old female mongrel cat. The mass showed infiltrative growth and caused deformation of the corpus callosum. Histopathologically, the tumour cells showed anaplasia, pleomorphism and mitotic figures. Necrosis and vascular proliferation were prominent. The neoplastic cells surrounded areas of necrosis, but as an indistinct pseudopalisade formation. Immunohistochemically, low numbers of tumour cells labelled positively for anti-glial fibrillary acidic protein and anti-S100 protein. Electron microscopically, the majority of tumour cells had no filaments and cytoplasmic processes, but the differentiated cells presented cytoplasmic filaments and glycogen granules. Based on these findings, the tumour was diagnosed as cerebral high-grade astrocytoma, glioblastoma.     

Extra-adrenal pheochromocytoma (paraganglioma) in a cat

Extra-adrenal pheochromocytoma (paraganglioma) arising from periadrenal tissue was diagnosed in an 18-year-old spayed domestic shorthair cat. The tumor was palpable on physical examination, but not apparent on plain radiographs. The cat developed temporary cardiac arrhythmia while the mass was being handled during excision, suggesting that the tumor was functional. The tumor was characterized histologically by nests and sheets of neoplastic cells separated by thin, vascular stroma. The cells had abundant eosinophilic granular cytoplasm and prominent nuclei. Diffuse, dark, intracytoplasmic granules were seen in sections stained with Grimelius stain. Ultrastructurally, the cells contained round and oblong, membrane-limited, dense core neurosecretory-type granules. Serotonin was detected in the cytoplasm of the neoplastic cells by use of immunocytochemical analysis.     

Hepatoblastoma in a cat

Hepatoblastomas are neoplasms that originate from putative pluripotential stem cells of the liver. A hepatic mass from an 8-year-old Abyssinian cat was composed of cords and sheets of neoplastic cells, with scattered rosettes and small ductal structures. Most neoplastic cells had a pale eosinophilic cytoplasm and a round to ovoid nucleus. The tumor also had short spindle cells with an oval nucleus. Immunohistochemically, neoplastic cells were weakly positive for embryonic hepatocellular markers, such as alpha-fetoprotein and cytokeratin (CK) 8/18, but negative for the hepatocellular marker Hepatocyte Paraffin 1. The cells were also positive for CD56/neural cell adhesion molecule and for the biliary epithelial markers CK 7, CK 8/18, CK CAM5.2, and vimentin, but negative for CK 20. Some neoplastic cells expressed neuroectodermal or neuroendocrine markers, such as protein gene product 9.5 and synaptophysin, but were negative for chromogranin A and not argyrophilic by the Grimelius technique. The cat died soon after the biopsy without clinical improvement.     

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.     

Pheochromocytoma Presenting as Acute Retroperitoneal Hemorrhage in a Dog

Objective: This report describes the perioperative management of a dog with a right adrenal pheochromocytoma that presented with acute retroperitoneal hemorrhage, cardiac arrhythmia and hypertension. Additionally, a summary of pheochromocytoma and the idiosyncrasies of perioperative management of a pheochromocytoma are provided.
Summary: A 7-year old male, neutered, Dalmation was presented for acute collapse, abdominal pain and tachycardia. Physical examination findings were consistent with hypoperfusion concurrent with multiple cardiac arrhythmias and hypertension. Abdominal ultrasound revealed retroperitoneal effusion and a right adrenal mass intimately associated with the caudal vena cava. Incomplete right adrenalectomy was performed. Histopathology confirmed a pheochromocytoma.
Unique information provided: To the authors' knowledge, this is the first definitive report of acute retroperitoneal hemorrhage as the initial clinical manifestation of histologically confirmed adrenal pheochromocytoma in the dog. ( J. Vet Emerg Crit Care 2001; 11(3): 221–227 )     

A rhabdomyosarcoma arising in the larynx of a dog

A neoplastic nodular lesion, 2 × 3 cm in diameter, was found in the larynx of a 6-year-old spayed female dog. The tumor was ill-circumscribed, consisting histologically of large round cells with abundant cytoplasm interspersed with small round cells with less cytoplasm and occasional multinucleated cells (myotubes). Immunohistochemically, tumor cells were positive for myoglobin, desmin and vimentin in varying degrees, but negative for S-100 protein, GFAP or cytokeratin. Cytoplasmic myofilaments/myofibrils with a dense Z-line-like structure were seen, the fine structures of which were complemented by PTAH stain. Based on these findings, the tumor was diagnosed as a rhabdomyosarcoma, a very rare tumor in the larynx of dogs.     

49-month survival following caval venectomy without nephrectomy in a dog with a pheochromocytoma

An 11 yr old spayed female Labrador retriever was diagnosed with a right adrenal tumor. At surgery, adhesions to the right kidney were dissected, allowing the right kidney to be preserved. The tumor showed extensive invasion into the suprarenal vena cava. It was felt that thrombus removal via venotomy could not be performed. Instead, the vena cava was ligated caudal to the liver and cranial to the right renal vein. The neoplastic gland was then excised en bloc together with the portion of the invaded caudal vena cava. Hind limb edema had developed preoperatively and increased transiently in the first days postoperatively. The animal was discharged 6 days postoperatively with no other clinical disorders, and hind limb edema resolved over time. Histopathology identified a pheochromocytoma. The dog died 49 mo later. A neoplastic thrombus of the vena cava may require venotomy to allow thrombus removal. Occasionally, removal of the thrombus by venotomy may prove impossible. In such a situation, en bloc removal of the concerned portion of the vena cava may be performed with a good long-term outcome provided that gradual occlusion of the vena cava by the thrombus has allowed time for collateral circulation to develop.     

Erythrophagocytic multiple myeloma in a cat

A 7-year-old neutered male domestic shorthair cat was presented to the Veterinary Medical Teaching Hospital at the University of Georgia for further evaluation of a suspected osteolytic lesion of the left 10th rib. Results of a CBC and biochemistry profile revealed mild nonregenerative anemia, hyperproteinemia, hyperglobulinemia, and hypercalcemia. Serum protein electrophoresis was consistent with a monoclonal gammopathy. Marked proteinuria with an increased urine protein to creatinine ratio was found. Cytologic examination of the liver, spleen, and bone marrow revealed numerous plasma cells, many of which were erythrophagocytic. Within the bone marrow, the plasma cells contained phagocytosed metarubricytes in addition to phagocytosed erythrocytes. A diagnosis of erythrophagocytic multiple myeloma was made and treatment with prednisone and melphalan was begun. Four weeks after presentation, the cat was euthanized due to clinical deterioration. A complete necropsy was performed. The distal one-third of the left 10th rib was completely absent. Histologically, there was no evidence for osteolysis or neoplastic cells in the remaining portion of the rib. However, large sheets of plasma cells were found infiltrating the spleen and bone marrow. Moderate erythrophagocytosis by the plasma cells was observed in both organs. The plasma cells, including the erythrophagocytic cells, were positive for CD79alpha by immunohistochemical staining. Erythrophagocytosis by plasma cells as a cause of anemia is uncommon in people with multiple myeloma and is rare in animals. To our knowledge, this is the first report of erythrophagocytic plasma cells in a cat with multiple myeloma.     

A canine peripheral nerve sheath tumor including peripheral nerve fibers

Peripheral nerve sheath tumor was found in a 7-year-old male mongrel dog. The tumors were located in the right cheek subcutis and oral submucosa. Histologically, neoplastic cells were arranged in streaming bundles, occasionally interlacing bundles or whorls of elongated and spindle cells. Cellular atypia was poor and mitotic figures were rarely observed. Ultrastructurally, neoplastic cells had basement membrane, typical of Schwann cells. One bundle of normal peripheral nerve fibers and some myelinated axons were seen within the tumor tissues. Immunohistochemically, neoplastic cells reacted to vimentin, glial fibrillary acidic protein, S-100 protein and neuron specific enolase. In addition to the above immunoreactions, the included nerve fibers were positive for myelin basic protein and neurofilament protein. This paper also discusses immunohistochemical findings on differential diagnosis in comparison with those of canine hemangiopericytomas reported hitherto.     

Spontaneous Mammary Adenocarcinoma in a Twelve-week-old Female Sprague-Dawley Rat

Spontaneous mammary adenocarcinoma was observed in a 12-week-old female SD rat. A movable mass in the right cervical region was found at 11 weeks of age, and the rat was sacrificed the following week. The mass was located in the vicinity of the right salivary gland and measured 38 mm × 26 mm × 16 mm in gross size. It was a firm whitish mass, with a cut surface that was also whitish in appearance. Histopathologically, neoplastic cells formed glandular structures that contained secreted eosinophilic material. Ultrastructurally, similar secreted material and lipid droplets were in the cytoplasm of the neoplastic cells. Immunohistochemically, the neoplastic cells were positive for cytokeratin 8, cytokeratin 18 and estrogen receptor α. Based on these findings, the tumor was diagnosed as a mammary gland adenocarcinoma, and we therefore conclude that this tumor type can occur spontaneously in female SD rats as young as 12 weeks of age.     

Immunohistochemical characterization of a hepatic neuroendocrine carcinoma in a cat.

A hepatic mass was identified in a 5-year-old, female mixed-breed cat that died spontaneously after a clinical history of progressive emaciation, ptyalism, and persistent coryza. At necropsy, a 7-cm-diameter, yellow-brown, firm, multilobulated tumor was identified in the liver. Microscopically, the mass consisted of neoplastic cells arranged in small, closely packed nests within a thin fibrovascular stroma. These cells were of medium sized and polygonal, with fine argyrophilic cytoplasmic granules. Nuclei were predominantly round with finely stippled chromatin and indistinct nucleoli. Mitotic figures were numerous. Immunohistochemically, most of the neoplastic cells were immunoreactive for chromogranin A, neuron-specific enolase (NSE), and cytokeratin AE1/AE3 and weakly labeled for synaptophysin. The tumor was negative for glial fibrillary acidic protein (GFAP), vimentin, and cytokeratins 5, 6, 8, and 17. Vascular emboli and intrahepatic micrometastasis were also identified with chromogranin A. All these features were consistent with a hepatic neuroendocrine carcinoma and emphasized the importance of using a panel of antibodies to diagnose such rare tumors.     

Malignant pheochromocytoma presenting as a bradyarrhythmia in a dog

Objective: To describe a case of atrioventricular block and syncope secondary to systemic hypertension in a dog with malignant pheochromocytoma. Case Summary: A 13‐year‐old spayed female mixed‐breed dog presented following an acute onset of collapse. The dog was hypertensive and had paradoxical high‐grade second‐degree atrioventricular block with concurrent syncope. Initial emergent therapy included a nitroprusside infusion for the systemic hypertension and vagolytic therapy for the bradyarrhythmia. A left adrenal mass was seen on abdominal ultrasound and was further characterized by MRI. Following medical stabilization with phenoxybenzamine and propantheline, a left adrenalectomy was performed. Histological diagnosis was consistent with a malignant pheochromocytoma. Following tumor removal there has been no further hypertension, atrioventricular block or syncope. Unique information provided: This is the first documented case of a malignant pheochromocytoma presenting as syncope secondary to hypertension induced atrioventricular block.     

CANINE INTRACRANIAL EPIDERMOID CYST

A 7-year-old intact male pitbull presented with a 2-month history of progressive dysequilibrium. Cerebrospinal fluid analysis was indicative of a central inflammatory or neoplastic disorder. A cerebellar cystic structure was identified on magnetic resonance imaging which was found to be an epidermoid cyst on histopathology.     

Alveolar type II cells expressing jaagsiekte sheep retrovirus capsid protein and surfactant proteins are the predominant neoplastic cell type in ovine pulmonary adenocarcinoma

Ovine pulmonary adenocarcinoma is caused by jaagsiekte sheep retrovirus. To gain insight into the histogenesis and viral pathogenesis of this neoplasm, the tumor cell phenotypes and differentiation state were correlated with the distribution of jaagsiekte sheep retrovirus capsid protein in neoplastic and normal cells of the lung in nine naturally occurring and 12 experimentally induced cases of ovine pulmonary adenocarcinoma. Overall, 82% of tumor cells had ultrastructural features consistent with alveolar type II cells, 7% of tumor cells had features of Clara cells, and 11% of tumor cells were insufficiently differentiated to classify. The proportion of the neoplastic cell phenotypes varied within tumors, and no tumor consisted of a morphologically uniform cell population. To further characterize the neoplastic cell population, sections of tumors were immunostained with antibodies to surfactant protein A, surfactant protein C, and Clara cell 10-kd protein. Overall, surfactant proteins A and C were expressed in 70% and 80% of tumor cells, respectively, whereas Clara cell 10-kd protein was expressed in 17% of tumor cells. Jaagsiekte sheep retrovirus capsid protein was detected in 71% of tumor cells and in macrophages (5/21 tumors examined) and in nonneoplastic alveolar and bronchiolar cells (6/14 tumors). Expression of this viral protein in neoplastic cells, classified morphologically and by immunophenotyping primarily as of the alveolar type II lineage, implies an important role for specific virus-cell interactions in the pathogenesis of ovine pulmonary adenocarcinoma.     

Characterization of cytoplasmic hyaline bodies in a hepatocellular carcinoma of a dog

This report describes the morphological and immunohistochemical features of intracytoplasmic inclusion bodies found in a 13-year-old Yorkshire dog with a hepatocellular carcinoma and referred for anorexia, lethargy and mild polydipsia. Fine-needle aspirates of the large abdominal mass revealed high number of pleomorphic neoplastic hepatocytes, containing round to polygonal, well-demarcated, hyaline bodies. Same findings were histologically confirmed on multiple biopsies. Immunohistochemically, the inclusion bodies were negative for alpha-1-antitrypsin, carcinoembryonary antigen, fibrinogen, IgG, IgM, cytokeratins 7, 8, 18, 19, 20. By transmission electron microscopy, the cytoplasmic inclusions were composed of granular homogeneous or reticulated electrondense matrix, enclosed within dilated rough endoplasmic reticulum or remnants of its membranes, consistent with proteinaceous material accumulated within neoplastic hepatocytes due to aberrant protein secretion or transport. This is the first detailed characterization of hyaline cytoplasmic inclusion bodies in canine hepatocellular carcinoma.     

Nasal and oral masses in a dog

A 5-year-old, intact male, stray dog was presented in poor body condition, with pallor, muzzle deformity, multiple oozing fistulas with grass awns, bilateral sanguinopurulent nasal discharge and a fleshy friable mass occupying part of the hard palate. A friable mass occupying both nasal cavities was found on rhinoscopy. The dog had moderate nonregenerative normochromic-microcytic anemia, thrombocytopenia, hyperglobulinemia, and hypoalbuminemia. Cytologic preparations of the nasal and oral masses contained a neoplastic population of round cells with intracytoplasmic and extracellular vacuoles. Leishmania amastigotes also were observed, in the cytoplasm of macrophages and, occasionally, within neoplastic cells. A diagnosis of transmissible venereal tumor and concurrent leishmaniosis was made. Treatment with vincristine and allopurinol resulted in complete resolution of clinical signs and disappearance of the masses. The presence of amastigotes in neoplastic TVT cells may suggest an alternative mode of transmission of canine leishmaniosis where these diseases co-exist.