Megakaryocytic leukemia; identification utilizing anti-factor VIII immunoperoxidase.

Coagulation Factor VIII is produced by endothelial cells and megakaryocytes. Antibody directed against Factor VIII or its associated antigens has been shown to be a sensitive marker for both normal and neoplastic endothelial cells. Its use to identify neoplastic megakaryocytes has not been described. We used immunoperoxidase localization of Factor VIII to identify megakaryocytes and immature megakaryocytic precursors in a case of megakaryocytic leukemia.