Erythropoietin-dependent erythrocytosis associated with hepatic angiosarcoma.

Erythropoietin (Ep) dependent erythrocytosis was discovered in a 77-year old man with angiosarcoma involving the liver and spleen. At autopsy, tissue from tumorous and normal sections of liver was obtained and extracts prepared for Ep assay in exhypoxic polycythemic mice. Neither tumor nor normal extracts had Ep activity; however, when the extracts were incubated with normal plasma prior to assay, significant amounts of Ep were generated. The normal liver tissue had three times the activity of the tumorous portion, 0.21 U/ml. These results suggest that the tissue contained an Ep activator, probably erythrogenin. It is proposed that the greater amount of erythrogenin activity in the normal tissue may reflect an attempt at liver regeneration following damage by an invading tumor, as regenerating liver has been identified as a stimulus for extrarenal EP and erythrogenin production.