Clonal evolution from trisomy into tetrasomy of chromosome 8 associated with the development of acute myeloid leukemia from myelodysplastic syndrome

Tetrasomy 8, though rare, is usually associated with trisomy 8, a far more common chromosomal abnormality in acute myeloid leukemia (AML). Yet the clo nal relationship between trisomy 8 and tetrasomy 8 in the cases with these chromosomal abnormalities has been unclear. Here, we report a case of a 17- year-old male, diagnosed as having a myelodysplastic syndrome (MDS). Chromo some analysis showed the presence of trisomy 8. Five years later, he develo ped overt AML exhibiting tetrasomy 8 only. After chemotherapy, the blast ce lls in the bone marrow decreased to 3.4%, and the karyotype showed trisomy 8 alone. Fluorescence in situ hybridization using a probe specific for chro mosome 8 showed that the percentages of cells exhibiting 2/3/4 signals were 7.8/89.2/2.0 at the MDS stage, 20.5/36.1/41.0 when overt AML developed and 24.0/72.1/2.4 after chemotherapy. These results suggested that tetrasomy 8 is derived from the AML clone, possibly evolved from the MDS clone with tr isomy 8. To our knowledge, this is the first detailed case report of clonal evolution from trisomy 8 into tetrasomy 8 associated with the development of AML from MDS. (C) 2001 Elsevier Science Inc. All rights reserved.