Budd-Chiari syndrome caused by undifferentiated small round cell tumor of the liver in an adult.

An undifferentiated small round cell tumor of the liver in a 60 year old black male is described. Although the light microscopic findings in this tumor were strongly suggestive of embryonal rhabdomyosarcoma, the ultrastructural study disclosed no myofibrils or other specific characteristics. Thus, we classify this tumor as an embryonic tumor or primitive mesenchymal tumor of the liver.