Acquired 11q23/MLL rearrangement of unknown clinical significance

Newly emerged 11q23/MLL rearrangements in patients with a prior history of cytotoxic therapies are almost always associated with therapy-related hematological malignancies. Here we report a patient who had received various chemotherapies for his chronic lymphocytic leukemia (CLL). An abnormal clone of t(3;11)(p13;q23) was detected in 7 out of 20 metaphases in the bone marrow (BM) in the 15^th year of disease. MLL rearrangement was detected in myeloid and erythroid cells, not in CLL cells by combined morphologic and fluorescence in situ hybridization. BM showed no evidence of myelodysplasia or increased blasts. Patient had been closely followed for 3 years, the abnormal clone was persistently detected but the patient had normal blood counts and normal BM examinations. This is the first case to show MLL rearrangement of unknown clinical significance in the setting of post cytotoxic chemotherapy.