Acute promyelocytic leukaemia (M3): relapse with acute myeloblastic leukaemia (M2) and dic(5;17) (q11;p11)

Secondary leukaemia following treatment of M3 acute promyelocytic leukaemia (APL) is a rare event. We describe a patient in remission following chemotherapy for APL who relapsed with M2 acute non-lymphoblastic leukaemia (ANLL). The original t(15;17) (q22;q21) chromosome translocation was lost and replaced by a clone containing a dic(5;17) (q11;p11) abnormality. Southern genomic analysis demonstrated re-arrangements of the retinoic acid receptor varies; is directly proportional to (RAR varies; is directly proportional to) and PML genes in the APL blasts at presentation but not in the M2 ANLL marrow at relapse. The significance of unbalanced 5;17 translocations as markers for therapy-related secondary leukaemia is discussed.