Biphenotypic or mixed lineage leukaemia (Bi-AL) is an uncommon type of acute leukaemia which has been associated with a poor outcome. During the 7-year period 1989-95 we treated 238 leukaemic patients (age: 0-15 yrs) and we identified 6 cases of Bi-AL (2.5% of all leukaemias). Their diagnosis was retrospectively based on the morphological, cytochemical & immunological criteria proposed by the EGIL group (Leukemia [1995]; 9: p1783-86). Median age was 11 yrs (range 5-15) and the M:F ratio was 2:1. All patients had de novo leukaemia and presented with >50% circulating blasts, regardless of the Wbc count. Chromosomal abnormalities were identified in all of them; a Ph(+)ve clone was found in 2/6 (33%) and a t(11;19) in one case. CNS involvement was found in 2 children at diagnosis (No 3,4) while 4/6 (66%) had lymphadenopathy and/or organomegaly. Table 3/6 children(cases 2,3,4) were treated with UKALL protocols and case 6 with AML therapy. Cases 1,5 received a hybrid regime. Four patients were transplanted; 2/4 of these died in remission in the early post-BMT period from chest infections. The median overall survival and DFS are 34 months (range: 4-71) and 29 months respectively. Our results indicate true Bi-AL is rare and strongly associated with poor prognostic features while agressive treatment may not change the dismal outcome.

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