Large cell transformation of Sezary syndrome - A conventional and molecular cytogenetic study

Hyperdiploidy sometimes is found in mycosis fungoides-Sezary syndrome, but its diagnostic significance remains undefined. We report an unusual case of Sezary syndrome manifesting with leukemic large cell transformation. Conve ntional karyotypic analysis showed the presence of a near-tetraploid neopla stic clone. With dual-color cytometric analysis, we showed that the large S ezary cells were near-tetraploid with a DNA index of 1.86, thereby demonstr ating a direct relationship between cell size and ploidy. Comparative genom ic hybridization further showed chromosomal imbalances that were not reveal ed on conventional karyotyping. Our findings suggest that hyperdiploidy may be a marker of large cell transformation, so that when this karyotypic abn ormality in mycosis fungoides-Sezary syndrome, a search for such a complica tion is indicated.