T-cell acute lymphoblastic leukemia occurring in a patient with acute promyelocytic leukemia.

Secondary acute lymphoblastic leukemia (sALL) following acute myeloid leukemia (AML) is a rare event; only eight cases have been reported. We report a patient with acute promyelocytic leukemia (APL), in hematological and molecular remission who developed T-ALL three years after the diagnosis of APL. The morphological, cytochemical, phenotypical and molecular features of this T-ALL were different from those of the previous APL. The absence of t(15;17), negative PML/RAR alpha at reverse transcription polymerase chain reaction (RT-PCR) analysis and presence of TcR delta support the hypothesis that the T-ALL in this sALL case originated from a different clone from that of the APL cells.