Erythroblastic transformation in myeloproliferative disorders: confirmation by an immunohistologic technique.

Blast crisis developed in 2 patients with meyloproliferative disorders, 1 with chronic granulocytic leukemia and the other with myelosclerosis and myeloid metaplasia. The blast cells had the morphologic and histologic characteristics of erythroblasts. An immunohistologic technique capable of detecting intracellular hemoglobin was used in order to demonstrate that these blast cells were of erythroid nature. The occurrence of erythroblast transformation in myelosclerosis and myeloid metaplasia as well as in chronic granulocytic leukemia supports the concept that both conditions are disorders of the marrow stem cell that may display similar morphologic, cytochemical and immunologic expressions in blast crisis. This study demonstrates that immunohistologic techniques are potentially valuable in the study of myeloproliferative disorders.