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Large Cell Transformation of Sézary Syndrome
A Conventional and Molecular Cytogenetic Study

Chi-chiu So MBBS, Kit-fai Wong FRCPath, Lisa L.P. Siu MSc, Yok-lam Kwong MD
DOI: http://dx.doi.org/10.1309/4E9V-HBY1-TMBM-K3BY 792-797 First published online: 1 June 2000


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.

Key Words:
  • Mycosis fungoides
  • Sézary syndrome
  • Large cell transformation
  • Polyploidy
  • Cytogenetics
  • DNA ploidy
  • Comparative genomic hybridization