Large Cell Transformation of Sézary Syndrome

Abstract

Hyperdiploidy sometimes is found in mycosis fungoides–Sézary syndrome, but its diagnostic significance remains undefined. We report an unusual case of Sézary syndrome manifesting with leukemic large cell transformation. Conventional karyotypic analysis showed the presence of a near-tetraploid neoplastic clone. With dual-color cytometric analysis, we showed that the large Sézary cells were neartetraploid with a DNA index of 1.86, thereby demonstrating a direct relationship between cell size and ploidy. Comparative genomic hybridization further showed chromosomal imbalances that were not revealed on conventional karyotyping. Our findings suggest that hyperdiploidy may be a marker of large cell transformation, so that when this karyotypic abnormality is found in mycosis fungoides–Sézary syndrome, a search for such a complication is indicated.