Epithelioid hemangioendothelioma in the right auricle of an adult, male Rhesus macaque (Macaca mulatta)
A 9-year-old, male castrate, Rhesus macaque was euthanized following a prolonged history of chronic renal failure. Necropsy revealed a proliferative lesion within the right cardiac auricle composed of neoplastic epithelioid cells which infiltrated the myocardium and frequently exhibited intracytoplasmic luminae. Cells multifocally exhibited strong cytoplasmic immunoreactivity for Factor VIII-related protein (von Willebrand's factor). The histological characteristics of this tumor are consistent with a diagnosis of epithelioid hemangioendothelioma, an intermediate-grade vasoformative neoplasm which has to our knowledge not previously been reported in the heart of a non-human species.