Atypical chronic myelogenous leukemia (aCML) is a leukemic disorder that exhibits both myelodysplastic and myeloproliferative features at the time of diagnosis. What this means is that it is not truly a CML but a condition that can be confused with CML, but is essentially different. It is not very common. It is thought that these features denote a poor prognosis, but these cases ahve a variety of genetic abnormalities that are different from CML and not much is known about how theya ffect prognosis. Atypical CML cases are usually BCR-ABL negative. The optimal treatment of aCML is uncertain because of the rare incidence of this chronic leukemic disorder. Treatment with hydroxyurea may lead to short-lived partial remissions of 2- to 4-months’ duration. Atypical CML, appears to respond poorly to treatment with interferon-alpha or other CML treatments.
For Professional version see here