Additional chromosome abnormalities in transient abnormal myelopoiesis in Down's syndrome patients.

We report a case of transient abnormal myelopoiesis (TAM) with Down's syndrome. As the blast cells had additional chromosome abnormalities (50,XY,+12,+14,+21 x 2), a possibility of acute leukemia was considered from a cytogenetic point of view. But the abnormal clone gradually disappeared without antileukemic therapies. Viewing it together with previous reports of TAM with additional chromosome abnormalities in Down's syndrome babies, its presence does not immediately indicate an aggressive clinical course as in acute leukemia and spontaneous complete hematological remission may be achieved. Thus, a careful follow-up should precede cytogenetic findings helping to determine the therapeutic intervention.