Leiomyosarcoma of the pericardium, with epicardial metastases and peripheral eosinophilia in a dog.

A dog with a history of dyspnoea, anorexia and ascites showed on examination signs of right-sided heart failure, pleural effusion and peripheral eosinophilia. Diagnostic imaging suggested the presence of a mediastinal mass, and histopathological and immunohistochemical examination of a biopsy sample led to a diagnosis of leiomyosarcoma. On post-mortem examination, an extensive mass was found, which encircled the heart and obliterated the pericardial sac, with probable metastatic spread to the epicardium. Eosinophilic infiltration of the neoplastic mass, lamina propria of the stomach and duodenum, interstitium of the kidney, and submucosa of the bladder was consistent with a possible paraneoplastic eosinophilia.