[Biclonal leukemia O-ALL/AMoL) with 11;19 translocation and trisomy X in an 8-month-old girl].

Biclonal leukemia was diagnosed in an 8 months old girl, combining lymphoblastic (FAB L1) and monoblastic (FAB M 5) phenotypes which were classified as O-ALL and AMol by immunological examination of surface-antigens. Chemotherapy for one cell type resulted in predominance or relapse of the other one. Chromosomal abnormalities diagnosed in the lymphoblastic clone consisted of translocation t(11;19)(q23;p13) and triple X. The breakpoint 11q23 neighbouring one well known oncogene (ets) is not strictly associated with special leukemic phenotypes. But it is often found in infants and usually correlated with a poor prognosis. The data of 18 patients with hybrid leukemias registered in the BFM studies strongly support the fatal course of the disease. 12 months after diagnosis approximately 1 out of 10 children is expected to survive disease-free.