ABSTRACT
This entity, referred to as acute myelomonocytic leukem ia w ith abnormal marrow eosinophils (AM M Leo), is morphologically equivalent to A M M L (M 4) w ith the addition o f increased abnormal eosinophils. These genetic defects occur in about 5% to 8% of AM Ls. The abnormal eosinophils dem onstrate the fu ll range of maturation, w ith large purple granules seen mostly in the eosinophilic promyelocyte and eosinophilic myelocyte stages. The im mature eosinophils may demonstrate hypolobation. Chloracetate esterase is weakly positive in the eosinophils in contrast to normal eosinophils that are characteristically negative. Rare cases lack the eosinophilic component. Mature neutrophils are decreased in the BM. Some cases have slightly less than 20% blasts but should still be diagnosed as AM L. FISH and PC R are more sensi tive for detecting these chromosome 16 abnormalities and should be done in all cases in which this disease is suspected based on morphology because o f the therapeutic significance. Some patients present w ith myeloid sarcoma. The prognosis is superior to equivalent leukemias lacking the chromosome 16 abnormalities and is made better by treatment w ith high-dose су tarabine given during the consolidation phase o f therapy.
