Tetraploid cell line in a girl with acute leukaemia.

In a girl with atypical acute leukaemia the malignant cell line in peripheral blood and bone marrow during these relapses was found to be tetraploid. The abnormal cells were more proliferative than those usually present in acute leukaemia. The tetraploid DNA content of the blast cells distinguished them from other cells in blood and bone marrow from this patient and from the blast cells found in other instances of acute lymphoblastic leukaemia.