Exfoliative cytology in the diagnosis of diffuse mesothelioma in the dog. Illustration by a case report.

This report deals with a dog which was presented for ascites that appeard to be related to fluid accumulation in the pericardium. Subsequent to resection of the pericardium the ascites disappeared but a few months later there was fluid accumulation in the thorax. Cytological examination of the thoracic fluid revealed the cell aggregates ("cell balls") which are indicative of mesothelioma and this diagnosis was confirmed by the autopsy findings. The initial cytological diagnosis on the pericardial fluid, which was not in agreement with the histology of the excised pericardium, is also discussed.