Echocardiographic, thoracic ultrasonographic, and CTA diagnosis of pericardial neoplasia in a dog.

A 12-year-old male neutered Yorkshire Terrier presented for coughing and respiratory distress. Transthoracic echocardiography initially misdiagnosed the patient with pericardial effusion; repeat echocardiography increased suspicion for neoplasia. A definitive diagnosis was not apparent. Findings on thoracic computed tomography and thoracic ultrasound were consistent with a diffusely thickened, heterogenous, hypoechoic soft tissue structure surrounding the heart. Fine needle aspirates were obtained using ultrasound guidance and routine cytology of the intrapericardial mass was consistent with neoplasia, with pericardial mesothelioma most likely. These novel findings highlight the importance of thoracic ultrasound and potential limitations of echocardiography in diagnosis of pericardial neoplasia.

Clinical, CT, and ultrasonographic features of canine and feline pleural and peritoneal carcinomatosis and sarcomatosis.

Carcinomatosis and sarcomatosis describe the widespread dissemination of metastatic neoplastic cells throughout the body. Studies describing their clinical and imaging features in veterinary patients are limited. The objective of this retrospective, multicenter, cross-sectional study is to describe the clinical, ultrasonographic, and CT features of pleural and peritoneal carcinomatosis and sarcomatosis in dogs and cats to aid detection and differentiation of these lesions. Medical records and CT and ultrasonographic images were reviewed. Although a large degree of overlap was observed between the imaging features and clinical signs of canine and feline carcinomatosis and sarcomatosis, some distinguishing features were observed. Dogs were significantly more likely to present with abdominal pain compared to cats (P = .022), whereas cats more commonly presented with inappetence (P = .019). Dogs with sarcomatosis had a significantly heavier bodyweight than dogs with carcinomatosis (P = .005), largely due to a higher prevalence of splenic hemangiosarcoma in this patient cohort. Peritoneal effusion was more frequently observed in dogs with carcinomatosis compared to dogs with sarcomatosis (P = .021). Imaging and clinical features observed in this study may help to distinguish sarcomatosis and carcinomatosis lesions. Due to the large degree of overlap observed, cytological or histopathological analysis is recommended for definitive diagnosis.

Pleural mesothelioma in a California sea lion (Zalophus californianus).

A 25-year-old female California sea lion (Zalophus californianus) reared in an aquarium died following a history of anorexia, lethargy, abnormal protrusion of the skin, and oral respiration. At necropsy, multiple yellowish-white nodules with diameters of 0.1-0.5 cm were disseminated in the thoracic cavity and lungs. Histopathologically, the nodules were continuous with normal mesothelium and were characterized by the proliferation of spindle-shaped to polygonal neoplastic cells with prominent atypia. The neoplastic cells exhibited diffuse, strong staining for vimentin and partial, weak to moderate staining for cytokeratin AE1/AE3. Based on these findings, the lesions were diagnosed as pleural mesothelioma. This study reports the first case of pleural mesothelioma in California sea lion.

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.

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.

Pleuropulmonary blastoma in an equine fetus.

Pleuropulmonary blastoma (PPB) is a rare biphasic tumor of children formed by mixed epithelial-and-mesenchymal elements. In this article, the authors report a pulmonary mass in an equine fetus with characteristics of PPB. A soft multicystic broad-based pleural mass was identified in the right caudal lung lobe. The mass comprised solid areas of loose mesenchyme, fenestrated by small ducts or large cystic areas lined by cuboidal epithelium. Mesenchymal elements had moderate anisocytosis, anisokaryosis, and cellular pleomorphism and were immunoreactive for vimentin. Epithelial cells lining ducts and cystic lumina were nonciliated and cuboidal with central round nuclei, minimal cellular pleomorphism, and strong immunoreactivity for cytokeratin. Pertinent characteristics in common with human PPB were the pleural-based location, the dual solid or delicate multiloculated cystic structure, the primitive mesenchymatous stroma fenestrated by well-differentiated cuboidal epithelial-lined lumina, and the occurrence during gestation.

Localized pleural mesothelioma causing cranial vena cava syndrome in a dog.

A 9-year-old female crossbred dog was presented to the Hospital Universitario Veterinario Rof Codina (Universidad de Santiago de Compostela, Lugo, Spain) for acute onset of severe, progressive swelling of the head, neck, and cranial trunk. Survey radiographs and ultrasonography revealed a large, heterogeneous mass in the cranial mediastinum, compressing or growing into a large blood vessel within the cranial mediastinum and displacing the heart dorsocaudally. At postmortem examination, the mass was diagnosed as a large, localized mesothelioma. Localized mesotheliomas are rare neoplasms in dogs but should be considered as a possible differential diagnosis for cranial vena cava syndrome. The anatomic distribution and clinical features of mesothelioma in the present report are similar to other cases in humans.

Growth of adenocarcinoma from canine pleural fluid on aerobic bacterial culture.

We report a case of canine adenocarcinoma with multi-organ metastasis in which colonies of adenocarcinoma cells grew upon aerobic bacterial culture of pleural effusion. Stained agar colonies were highly similar to rare suspicious cells seen on cytologic examination of the pleural effusion, as well as rare cells seen on cytologic examination of pancreatic and gastric wall fine-needle aspirates. Cells from colonies growing on agar media were mildly immunoreactive for cytokeratin. Histologic examination of tissues obtained at autopsy revealed pancreatic adenocarcinoma with vascular invasion and nodal, gastric, pulmonary, and pleural metastasis.

A biphasic malignant mesothelioma of the peritoneum and pleura in a horse.

This report describes the macroscopic, histologic, immunohistologic and ultrastructural characteristics ofa biphasic malignant mesothelioma in the peritoneal and pleural cavity of a 13-year-old Icelandic pony mare, which exhibited recurrent ascites clinically. Immunohistology was performed employing multiple monoclonal antibodies against cytokeratins (CK) and vimentin. The ultrastructural examination included the quantitative evaluation of the length to diameter ratio of the microvilli. Post mortem examination revealed a severe ascites and hydrothorax. The serosal surfaces of the peritoneum and pleura displayed poorly-demarcated, multifocal to coalescing laminar masses and small nodules. Histology revealed a bimorphic mass consisting of spindle-shaped cells and microcystic epithelioid areas. A transcoelomic and local invasive growth pattern as well as lymph node metastases were noticed. Immunohistology revealed a strong expression of CK. Though a low and moderate expression of CK5/6 and CK20 was present, respectively, CK7 and CK10-antigens were lacking. Ultrastructurally, the epithelioid mesothelioma cells displayed long microvilli, cytoplasmic tonofilaments, and desmosomes. Quantitative evaluation of the length to diameter ratio of the 10 longest microvilli revealed a mean value of approximately 16.2. Summarized, this report described the case of a malignant biphasic mesothelioma with an atypical CK20 expression but a characteristic ultrastructural morphology including long microvilli.

Primary Pleural Squamous Cell Carcinoma in a Free-Ranging River Otter (Lontra canadensis).

An adult female North American river otter (Lontra canadensis) presented with multiple intrathoracic masses identified histologically as squamous cell carcinoma. Immunohistochemical staining patterns for high- molecular-weight keratin, p40, p63, calretinin, and TTF-1, along with the gross and histologic findings, indicated a primary pleural squamous cell carcinoma as the most likely diagnosis.

Peritoneal sarcomatoid mesothelioma in a sika deer.

A slaughtered 2-year-old female sika deer (Cervus nippon yesoensis) had diffusely distributed multinodular lesions on the serosal surface of the peritoneal cavity and several nodules in the pleural cavity. Histologically, they were composed of proliferating spindle-shaped neoplastic cells, arranged in a fascicular fashion. The cells in the invasive foci transitioned from a sarcomatoid to an epithelioid appearance. Immunohistochemically, both the spindle-shaped and epithelioid cells were at least focally positive for pancytokeratin, vimentin, calretinin, α-SMA, and desmin. From these findings, the deer was diagnosed with peritoneal sarcomatoid mesothelioma with metastasis to the pleural cavity. To our knowledge, this is the first reported case of peritoneal mesothelioma in a cervid species and the first case of mesothelioma in a sika deer.

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.

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.

Ten cases of feline mesothelioma: an immunohistochemical and ultrastructural study.

In the cat only 10 cases of mesothelioma, mainly of the peritoneum, have been previously reported. This paper describes a further 10 cases, eight pleural and two peritoneal, in males and females aged 1-17 years. Histologically, five tumours were epithelial, three fibrosarcomatous and two biphasic. Immunohistochemical markers used in human pathology for the identification of mesotheliomas include vimentin, cytokeratin (CK) AE1/AE3, HBME-1, CK 5/6, calretinin, thrombomodulin, carcinoembryonic antigen (CEA), CD15, E-cadherin and desmin. All 10 feline mesotheliomas were positive for vimentin and CK AE1/AE3, six were positive for HBME-1, two for CK5/6, three for CEA and four for E-cadherin. All were negative for desmin and calretinin. Antibodies to thrombomodulin and CD15 failed to cross-react with feline tissues. Electron microscopy, performed in four cases, revealed microvillar structures, desmosomes and intracytoplasmic lumina, confirming its value as a diagnostic tool. The study showed that mesothelial marker antibodies commonly used in human patients can be used for the diagnosis of feline mesothelioma, preferably as a panel of antibodies rather than only one.

Portal site metastasis of invasive mesothelioma after diagnostic thoracoscopy in a dog.

CASE DESCRIPTION: A 10-year-old Golden Retriever evaluated because of recurrent pericardial and pleural effusion underwent thoracoscopy with biopsy of the pleura and mediastinum. CLINICAL FINDINGS: Before thoracoscopy, 5 L of serosanguinous fluid was removed from the pleural cavity via thoracocentesis. During thoracoscopic exploration, it was observed that the parietal pleura and mediastinum were covered by miliary white to tan nodules 1 to 3 mm in diameter. Biopsy specimens were obtained, and partial pericardiectomy was performed. Portal sites were closed routinely. Cytologic evaluation of the pleural fluid revealed high protein concentration and cellularity, with cellular changes consistent with an exfoliating carcinoma. Results of bacterial culture were negative. TREATMENT AND OUTCOME: Carboplatin was administered via intracavitary instillation, and prednisone was administered orally. Twenty-one days later, 1 firm, irregularly shaped 6.5 x 3-cm mass and 4 smaller masses were detected in the area of the left thoracic wall where the cannula had been inserted during thoracoscopy. Histologic analysis of tissue from the masses collected at necropsy confirmed that they were malignant tumors with similar appearance to the pleural mesothelioma and immunohistochemical staining properties identical to those of the primary tumor. CLINICAL RELEVANCE: Although thoracoscopy is associated with less postoperative pain, shorter hospitalization times, and faster patient recovery than sternotomy procedures, complications are also possible with minimally invasive endoscopic surgery. Portal site metastasis can develop from contamination of portal sites with cells on instruments or cannulas or via leakage of effusion fluid. Although rare, this potential complication should be discussed with owners prior to performing the procedure.

Portal site metastasis after thoracoscopic resection of a cranial mediastinal mass in a dog.

CASE DESCRIPTION: An 11-year-old castrated male Vizsla was evaluated for excision of a cranial mediastinal mass. CLINICAL FINDINGS: The dog had a 1-month history of a cough that had recently increased in frequency. On physical examination, the dog had a grade 2/6 left systolic heart murmur and multiple subcutaneous masses. A soft tissue mass was observed in the cranioventral aspect of the thorax on radiographs. Results of a CT scan revealed a well-defined, 2.8 × 3.2 × 3.9-cm soft tissue mass in the cranial mediastinum. TREATMENT AND OUTCOME: The dog underwent video-assisted thoracoscopic removal of the mediastinal mass and recovered routinely. Histologic examination of excised tissues revealed malignant thymoma. Approximately 6.5 months after surgery, the dog was evaluated because of polyuria, polydipsia, decreased appetite, and vomiting. On physical examination, masses were found in both axillary regions. Results of serum biochemical analysis indicated hypercalcemia. Thoracic ultrasonography revealed pulmonary metastases and a large mass in the right caudoventral region of the thorax. The dog received supportive care and medical treatment for hypercalcemia, but clinical signs recurred. Euthanasia was elected; necropsy and histologic examination revealed thymic carcinoma. CONCLUSIONS AND CLINICAL RELEVANCE: Descriptions of the development of portal site metastasis in canine patients are rare. In this patient, portal site metastasis developed rapidly after thoracoscopic resection of a malignant thymic mass and was associated with hypercalcemia. As use of thoracoscopic procedures increases in veterinary medicine, it will be important to monitor the development of major complications such as those in the patient of this report.

Four cases of cell cannibalism in highly malignant feline and canine tumors.

Four cases of tumors in which cell internalization was frequently visualized are reported: one feline mammary carcinoma, one feline cutaneous squamous cell carcinoma, one canine pulmonary squamous cell carcinoma and one canine pleural mesothelioma. Cell internalization was observed by cytology in two of these cases (the feline mammary tumour and the pleural effusion in the canine mesothelioma) and by histopathology in all but the canine mesothelioma. Immunohistochemical staining for pancytokeratin was positive for both internalized and host cells, while E-cadherin expression was frequently absent, although internalized cells occasionally stained positive. This cell-to-cell interaction seems to be associated with tumors displaying a strong epithelial-mesenchymal transitional phenotype, in which cancer cells become engulfed by other cancer cells. Such event could be regarded as an important hallmark of very high malignancy.

Intrathoracic granular cell tumour in a dog.

Multiple granular cell tumours occurred diffusely throughout the pleura of an adult German Shepherd Dog. The growths were scattered over the surface of the lungs, mediastinum and diaphragm. Histologically, the masses consisted of plump cords of cells with eosinophilic, weakly PAS-positive cytoplasmic granules. Electron microscopically, the granules consisted of a pleomorphic population of electron-dense granules. The predilection site in the dog is the tongue and this is the first report of an intrathoracic, pleural site of granular cell tumours in the dog.

Cytology of diffuse mesothelioma in the thorax of a horse.

Examination of effusions from body cavities must include a search for neoplastic as well as inflammatory cells. Neoplastic cells found in the thorax are generally derived from adenocarcinomas or mesotheliomas. Mesotheliomas are relatively uncommon and the neoplastic cells found in effusions are difficult to differentiate from activated cells in inflammatory effusions. An ante-mortem diagnosis of mesothelioma was made in a mare on the basis of the large volume of fluid produced, the pleomorphic mesothelial cells, the polyp formation and the absence of PAS staining material after digestion of the cell impression with maltase diastase.

Clinical and pathological features of thoracic neoplasia in the horse.

Thirty-eight horses with confirmed thoracic neoplasia included 28 (37.7%) with lymphosarcoma, 4 (10.5%) with metastatic renal cell carcinoma, 2 (5.3%) with primary lung carcinoma, 2 (5.3%) with secondary squamous cell carcinoma from the stomach, 1 (2.6%) with pleural mesothelioma, and 1 (2.6%) with malignant melanoma. The major clinical features included weight loss, inappetence, dyspnoea and coughing, but in cases of lung metastases, they related more to the primary site of tumour formation. Haematological and serum biochemical abnormalities were non-specific. Specific pre-mortem diagnosis was made in 14 horses; this was most readily achieved when exfoliated neoplastic cells were present in pleural fluid.