RECURRENT LINEAGE SWITCH IN A CASE OF A T(4-11) INFANT LEUKEMIA AFTERBONE-MARROW TRANSPLANTATION - CASE-REPORT

Acute infant leukemia with a t(4;11) translocation has several high-ri sk features, such as hyperleukocytosis, extramedullary disease, and am biguous phenotypes. The prognosis is extremely poor. We report a patie nt with a t(4;11) acute leukemia, who presented an unusual phenotypic and cytogenetic course both before and after bone marrow transplantati on. At the time of diagnosis, leukemic cells revealed lymphoid feature s both morphologically and immunocytochemically (B lineage). However b one marrow blasts examined at the first relapse had monocytic features and were positive for esterase stain and CD13. The patient underwent bone marrow transplantation while in second remission, but again suffe red a relapse. The bone marrow blasts of the second relapse had the t( 4;11) translocation and were of lymphoid morphology, but were of T cel l lineage. The patient died without achieving bone marrow remission, T his is the first reported case of a recurrent lineage switch in a t(4; 11) infant leukemia after bone marrow transplantation.