Palliative intravenous cisplatin treatment for concurrent peritoneal and pleural mesothelioma in a dog

A 10-year-old Maltese dog was presented with abdominal distention and dyspnea. Cytological examination of pleural and peritoneal effusion was suggestive of malignant effusion of glandular origin. Numerous, multifocal, tan to white nodules were disseminated throughout the surface of the abdominal organs and peritoneum at biopsy. Histologically, the tumors were revealed to be an epithelial type of mesothelioma. Neoplastic cells co-expressed cytokeratin and vimentin. Intravenous administration of cisplatin was chosen as the treatment. During treatment, the dog's overall body condition improved and the clinical signs were relieved without significant side effects. The survival time from diagnosis to sudden death by unknown cause was 153 days.     

Systemic Listeria monocytogenes infection and concurrent pleural mesothelioma in a cat

Herein we describe a rare case of systemic Listeria monocytogenes infection with concurrent pleural mesothelioma in a stray cat that was found dead and submitted for autopsy. Gross pathology changes consisted of thoracic clear yellow fluid admixed with suspended fibrin strands; clear-to-tan, variably sized, <3 mm diameter pulmonary nodules; and enlargement of the submandibular, retropharyngeal, and prescapular lymph nodes. Histologic changes consisted of extensive areas of suppurative inflammation and necrosis with mineralization that partially effaced the pulmonary parenchyma and lymph nodes. Random, distinct necrotic foci were present throughout the hepatic parenchyma. Extending from the pleura, within perinecrotic alveolar spaces, and infiltrating the submandibular, retropharyngeal, and prescapular lymph nodes were dense sheets of neoplastic epithelioid cells with moderate pleomorphism and occasional karyomegaly and multinucleation. Neoplastic cells exhibited immunolabeling for pancytokeratin AE1/AE3 and vimentin, consistent with pleural mesothelioma. Aerobic bacterial culture of lung yielded heavy growth of L. monocytogenes. Immunohistochemistry (IHC) for L. monocytogenes revealed clusters of bacteria in the lung, lymph node, and liver. Pathologic changes were consistent with systemic listeriosis, confirmed by bacterial culture and IHC, and concurrent pleural mesothelioma.     

Lipid-rich pleural mesothelioma in a dog

An 11-year-old, neutered, male Golden Retriever cross dog was euthanized following a history of recurrent pericardial effusions. At necropsy, blood-tinged pericardial and intrathoracic effusions were seen along with numerous firm to hard plaque-like masses that studded the epicardial, pericardial, mediastinal, and costal pleural surfaces. Within the right thorax, the lesions coalesced into a large mass that occupied most of the cavity. Histologically, the masses were composed of solid sheets and papillary aggregates of medium-sized polygonal cells that contained abundant vacuolated to clear cytoplasm. Some of the cytoplasmic vacuoles stained positive with oil red O. The stroma contained metaplastic trabeculae of woven and lamellar bone. Immunohistochemically, the neoplastic cells expressed vimentin, pancytokeratin, and S-100 protein. Transmission electron microscopy corroborated the presence of intracytoplasmic vacuoles and demonstrated prominent intercellular junctional complexes and apically located microvilli. These findings are consistent with a lipid-rich variant of mesothelioma. To the authors' knowledge, this is the first report of a lipid-rich mesothelioma in a dog.     

Pleural mesothelioma in a young cat

A mesothelioma was seen as an incidental finding in the thoracic cavity of an eleven-month old female cat. At necropsy, the pale nodular lesions were spread over the ventral parts of the lungs and their corresponding parts of the diaphragm and the thoracic wall. Microscopically, the tumor consisted of mesenchymal tissue with large amounts of collagenous fibers covered by a mainly unilayered, polymorphic, partly vacuolated line of cells with large nuclei. Mitotic figures were rare. Based on morphological appearance the lesion was classified as an early mesothelioma.     

Palliative radiation therapy in a dog with malignant trichoepithelioma

An 11-year-old male Bearded Collie was brought to the Gifu University Animal Medical Centre with a skin mass on the lateral right thigh. Physical examination revealed a 30 × 65-mm oval mass with an alopecic and ulcerated surface. Histopathology of the surgically excised sample confirmed malignant trichoepithelioma. Five months after the surgery, the dog experienced lumbar pain resulting from metastasis to the lumbar vertebrae. Radiation therapy (RT) was performed and it alleviated the lumbar pain. Nine months after the surgery, multiple skin metastases were identified. RT was performed at each occurrence, which reduced the size of each tumour and resulted in a partial response; however, systemic metastasis occurred and the dog died 17 months after the initial surgery. Canine malignant trichoepithelioma is a rare tumour, so an effective treatment has not been determined. Data from our case study indicate that RT has potential for pain control of primary and metastatic malignant trichoepithelioma.     

Malignant pleural mesothelioma in a woodchuck (Marmota monax)

A spontaneous pleural mesothelioma was observed in a 4-year-old female woodchuck (Marmota monax). At necropsy, multifocal, tan to white, firm discrete nodules, 2 to 40 mm in diameter, were scattered over the ventral parts of the lungs and their corresponding parts of the diaphragm and the thoracic wall. Histopathologically, the tumor cells were large, cuboidal-shaped and variable size, and were weakly positive with PAS and Alcian blue. Immunohistochemically, neoplastic cells were positive for both vimentin and cytokeratin, indicating mesothelial origin. This report represents, as far as we know, the first reported case of a spontaneous mesothelioma in woodchucks.     

A case of biphasic mesothelioma with osseous and chondromatous differentiation in a cat

An 11-year-old domestic short hair cat with dyspnea, cyanosis, and pleural effusion died. Necropsy revealed several nodules and masses on the parietal pleura, pericardium, and diaphragm. The tumor contained epithelial and mesenchymal components and displayed osseous and chondromatous differentiation. Tumors cells were positive for pancytokeratin and vimentin. This is the first report of a biphasic mesothelioma with osseous and chondromatous differentiation in this species.     

Immunoglobulin A myeloma in a cat with pleural effusion and serum hyperviscosity

Immunoglobulin A myeloma, serum hyperviscosity, and septic pleuritis were diagnosed in a cat with pleural and peritoneal effusions. Serum hyperviscosity was determined by use of a WBC pipette, and clinical manifestations included retinopathy and cardiac changes. The presence of Salmonella typhimurium in the pleural fluid may have resulted from increased susceptibility to infection. Postmortem examination revealed plasma cell infiltration of the pleura, mesenteric lymph nodes, and the serosa of the intestine, liver, and spleen. This case represents an unusual form of myeloma in the cat.     

Malignant pleural mesothelioma in a female Lion (Panthera leo)

An 18-year-old female lion (Panthera leo) was referred to the Department of Animal Pathology of the University of Turin (Italy). At necropsy, multiple nodular, 4-20-mm, confluent white firm nodules were scattered throughout the pleural surfaces of the thoracic wall and of the lungs. Histological lesions were represented by proliferations of papillary structures lined by cuboidal basophilic mesothelial cells with large, oval nuclei and abundant granular eosinophilic cytoplasm. Immunohistochemistry revealed immunoreactivity for pancytokeratin and vimentin. None of the cells expressed calretinin antigen. Asbestos fibers and asbestos bodies were not detected respectively by light microscopy and by Scanning Electron Microscope-Energy Dispersive Spectrometer investigations. On the contrary, chrysotile asbestos were identified in samples from shelter material. Histological and immunohistochemical findings were consistent with the diagnosis of an epithelial malignant mesothelioma. To our best knowledge, this is the first report of a pleural mesothelioma in a lion.     

Malignant melanoma in pleural effusion in a 14-year-old cat

CASE DETAILS: A 14-year-old female cat presented with signs of respiratory distress. Pleural fluid was found on radiographic assessment. Cytologic evaluation of the fluid revealed malignant melanocytosis. The cat had a previous history of a recurrent malignant melanoma near the base of the right ear. Due to declining clinical condition, the cat was euthanized. CLINICAL SIGNIFICANCE: Cutaneous malignant melanomas (or melanosarcomas) are uncommon neoplasms in cats, and knowledge is limited. As far as the authors are aware, there are no previous reports in the veterinary literature of malignant melanocytes being identified in pleural effusion in cats, as they have in dogs. This report suggests that, despite conflicting information in the literature regarding the clinical behavior of cutaneous melanomas in cats, these tumors are capable of recurrence and metastasis. Aggressive treatment may be necessary even, as in this case, if the tumor is well differentiated on histopathology.     

Hyponatremia and hyperkalemia associated with chylous pleural and peritoneal effusion in a cat

A 6-year-old, castrated male shorthair was evaluated for chylous effusion in the thorax and abdomen. An underlying disease process was not determined. The cat developed hyponatremia and hyperkalemia, which was attributed to the mechanical drainage of pleural fluid and to the decreased urinary excretion of potassium.     

A suspected case of ornithine transcarbamylase deficiency in a cat

An 18 month-old, intact female American Shorthair cat was presented for evaluation of stunted growth and postprandial depression. Fasting serum ammonia and serum bile acid concentrations were above reference ranges at 396 microg/dl and 6.5 micromol/ l and their postprandial concentrations were 785 microg/dl and 9.5 micromol/l, respectively. The initial tentative diagnosis of a portosystemic shunt was excluded by mesenteric portography and histopathology of the liver. The cat was then suspected of a urea cycle enzyme deficiency and its urine was analyzed by gas chromatography-mass spectrometry. A presumptive diagnosis of ornithine transcarbamylase deficiency was made on the basis of the detection of orotic acid and uracil.     

Massive haemorrhage associated with inadvertent incision of a suspected carotid artery pseudoaneurysm in a cat

A 12‐year‐old, castrated male, domestic long‐haired cat experienced massive haemorrhage associated with an incision of a swelling on the neck 2 weeks after right‐sided ventral bulla osteotomy. Emergent control of haemorrhage was gained through unilateral carotid artery ligation. Cardiopulmonary resuscitation was provided in conjunction with massive blood transfusion. The cat made an unremarkable recovery. Carotid artery pseudoaneurysm due to surgical disruption of the carotid artery during ventral bulla osteotomy, specifically through the use of self‐retaining retractors, was suspected. This case highlights the development of pseudoaneurysm as a potential complication of head and neck surgery, and additionally describes a case of massive transfusion in a cat.     

Lung lobe torsion in association with a chronic diaphragmatic hernia and haemorrhagic pleural effusion in a cat

CLINICAL SUMMARY: This report describes torsion of the right cranial lung lobe in a cat with haemorrhagic pleural effusion and a chronic diaphragmatic hernia. Surgical treatment comprising lung lobectomy without de-rotation, and repair of the diaphragmatic defect, led to an uneventful recovery. PRACTICAL RELEVANCE: Lung lobe torsion is a rare condition in cats. While spontaneous lung lobe torsions may occur, a frequent association with underlying thoracic disease has been recognised in cats. However, neither haemorrhagic pleural effusion nor diaphragmatic hernia have been previously described in cats with lung lobe torsions, although they have been documented in dogs and humans. In a cat with suspected lung lobe torsion, a thorough search for an underlying disease should be undertaken.