RESUMEN
Early diagnosis of acute promyelocytic leukemia (APL) depends primarily on morphological recognition before the presence of t(15;17) or PML-RAR gene rearrangement is confirmed. But the diagnosis is difficult to be made, if typical APL morphologic features are not found. Here, we describe a 32- year old man who had been diagnosed as APL. He relapsed with AML M1 like phenotype, lacking the typical features of APL. At relapse, t(15;17) and PML-RAR alpha gene rearrangement were detected. After 14 days of chemotherapy and all-trans retinoic acid, the phenotype changed from the AML M1 like features to the typical hypergranular APL. Awareness of atypical morphologic subtypes found in APL is important. And identification of t(15;17) or PML/RAR alpha rearrangement will be helpful in diagnosis of atypical APL.