Extramedullary relapse despite graft-versus-leukemia effect after bone marrow transplantation in a girl with juvenile myelomonocytic leukemia

A 12 year-old girl with juvenile myelomonocytic leukemia (JMML) and monosom y 7 underwent allogeneic bone marrow transplantation (BMT) from her HLA-mat ched brother. To monitor the engraftment and the course of the disease we u sed fluorescence in situ hybridization (FISH) with probes specific for the centromeres of chromosomes X, Y and 7, Complete hematological remission was achieved and confirmed by the virtually exclusive presence of normal male cells in the bone marrow (BM). Acute graft-versus host disease (GVHD) was t reated with prednisone and cyclosporine A (CSA) and female cells with monos omy 7 reoccurred in the peripheral blood (PB) and BM. After discontinuation of the immunosuppressive therapy, the leukemic cells with monosomy 7 disap peared again from these compartments. One year after transplantation, isola ted extramedullary relapses occurred in lymph nodes and skin, followed by d issemination of blast cells into the BM, whereas the PB cells remained of d onor origin. The fact that the leukemic cells fluctuated with the intensity of the immunosuppressive treatment provides evidence of a graft versus leu kemia (GvL) effect in this unusually old girl with JMML with a unique extra medullary disease progression.