Splenic Hemangiosarcoma in a Young Sprague-Dawley Rat

The present report describes a rare case of spontaneous hemangiosarcoma in a nine-week-oldmale Sprague-Dawley rat. At necropsy, multiple white nodules of various sizes were observed onand within the enlarged spleen and liver and were histopathologically determined to be composedof spindle- to oval-shaped cells that showed invasive growth without encapsulation and werearranged solidly but partially in whorls or faint alveolar patterns with vascular-like spacescontaining small clefts or erythrocytes in the tumor mass. Immunohistochemical analysisrevealed that most of the tumor cells were strongly positive for vimentin, von Willebrandfactor (vWF) and CD34 but negative for podoplanin. In addition, electron microscopicexamination revealed the presence of Weibel-Palade bodies in the cytoplasm of the tumor cells.Based on these findings, this case was diagnosed as a hemangiosarcoma. The splenic masses werelarger than the hepatic ones, with tumor cells mainly observed at periportal regions with tumorembolism in the liver, suggesting that primary hemangiosarcoma initially developed in thespleen before metastasizing.