FLT3 internal tandem duplication in childhood acute myeloid leukaemia: association with hyperleucocytosis in acute promyelocytic leukaemia.

We evaluated the incidence of FLT3/internal tandem duplication (ITD) mutation in childhood acute myeloid leukaemia (AML) diagnosed over 15 years. FLT3/ITD was found in 10 of 45 (22.2%) non-acute promyelocytic leukaemia (non-APL) patients. The 5-year event-free survival of non-APL patients was higher in FLT3/ITD-negative versus -positive patients (48.9%, SE 8.9, vs 20.0%, SE 16.1, P = 0.03). In childhood APL, FLT3/ITD incidence was higher than in non-APL, although not statistically significant (10 out of 29 patients, 34.5%, P = 0.29). In APL patients, FLT3/ITD was strongly correlated to a higher white blood cell count at diagnosis and the M3 French-American-British subtype.