EN
An 8-year-old crossbred dog died suddenly with signs of shock. Necropsy revealed a cardiac tamponade caused by a perforating tumor in the right atrium. A similar tumor was found in the abdominal cavity. The histopathological and immunohistochemical examination showed that both tumors were composed of welldifferentiated pseudo-vascular structures, with endothelial cells that were positive for vimentin and von Willebrand factor, pericytes that were positive for vimentin and smooth muscle actin, and various amounts of collagen and reticulin fibers. The mitotic activity of tumor cells was low to moderate. Both tumors were consistent with Kaposi’s sarcoma that occurs in humans. On the basis of the histological features and immunohistochemical examination findings, both tumors were classified as Kaposi-like vascular tumors. This is the first report of a Kaposi-like vascular tumor with a unique, multicentric location and a fatal outcome in a dog.