Embolized mesothelial cells within mediastinal lymph nodes of three dogs with idiopathic haemorrhagic pericardial effusion.

Embolized mesothelial-like cells were detected within pericardial lymphatics and mediastinal lymph nodes of three golden retrievers with idiopathic haemorrhagic pericardial effusion. Morphological, cytochemical, and immunohistochemical investigations indicated that the embolized cells most likely originated from the pericardial mesothelium. None of the dogs showed evidence of an underlying neoplastic disorder. Such findings have not been reported previously in animals, but so-called "benign mesothelial cell inclusions" have been reported in mediastinal lymph nodes of human patients with pleuritis and pericarditis but no history of neoplasia. The present findings in dogs indicate the need to distinguish between lymphatic emboli arising from reactive mesothelial cells and metastases arising from a mesothelioma.