Metastatic malignant mesothelioma in a Bengal tiger

The fifteen year old male Bengal tiger (Panthera tigristigris) carcass was received for necropsy examination from Sepahijala Zoological Park, Tripura with the history of weakness, debility and anorexia. On necropsy examination, 2.5-3 litres of serosanguin- eous blood tinged fluid was observed in the pleural cavity. Most part of the pericardium was found to be velvety and thickened due to presence of multilobular often coalescing nodular grey-yellow coloured growths with irregular surface. Multifocal to coalescingvariable sized flat to occasionally depressed cream coloured necrotic areas were observed scattered throughout lungs. Liver and spleen also showed variable sized flat to occasionally raised nodular growths scattered throughout the parenchyma. Histologically, multiple neoplastic foci of epithelioid mesothelial cells showing malignant features were observed in the pericardium. Lungs revealed similar proliferation of neoplastic cells in a papillary pattern invading the alveoli. There were multifocal necrotic areas with amorphous eosinophilic material and karyorrhectic debris. The spleen and liver also showed similar neoplastic areas. On the basis of histological findings, the diagnosis was made as malignant pericardial mesothelioma.