The acute erythroleukemias

Acute erythroleukemia is an aggressive leukemia derived from a multipotenti al stem cell. Three subtypes have been described: M6a with greater than or equal to 3 30% blasts of the nonerythrocytic component, M6b with greater th an or equal to 30% pronormoblasts of the erythrocytic elements, and M6c wit h greater than or equal to 30% blasts and greater than or equal to 30% pron ormoblasts by the aforementioned exclusion criteria. The poor prognosis ass ociated with this disorder positively correlates with a high pronormoblast: myeloblast ratio, "unfavorable" cytogenetic aberrations, a high proliferati ve index, and the presence of P-glycoprotein expression (multi-drug resista nce phenotype). Chemotherapeutic regimens, directed toward these specific p arameters, should be devised in order to improve the characteristically poo r outcome of tl-lis patient population.