Genetic characterization of Sézary's syndrome by conventional cytogenetics and cross-species color banding fluorescent in situ hybridization

Background and Objectives. Sézary's syndrome is a peripheral T-cell neoplasm characterized by a pruritic exfoliative or infiltrated erythroderma, lymphadenopathies, and atypical T lymphocytes in the peripheral blood. Cytogenetic studies are scarce. This study was designed to increase cytogenetic information on this disorder. Design and Methods. Peripheral blood samples were collected from 21 patients with Sézary's syndrome (10 men, 11 women, mean age 64 years) and analyzed by conventional cytogenetics (72-hr cultures with phytohemagglutinin). For a better characterization of multiple chromosomal rearrangements, cross-species color banding (RxFISH) was used in four cases. Results. Fifteen (71.4%) of the 21 cases showed cytogenetic aberrations, with the karyotype being complex in 14. Among the 15 patients with an abnormal karyotype, 8 presented a diploid/near-diploid karyotype and 7 a near-tetraploid karyotype. The chromosomes most frequently involved were 1, 6, 8, 9, 10, 11, and 17. The most common structural rearrangements affected 1q, 2q, 6q23-27, and 8q22. Monosomies of chromosomes 9 and 10 and trisomies of chromosome 18 were recurrently observed. A statistical trend between abnormal and complex karyotypes, the presence of monosomy 10, the number of Sézary cells, and a decreased overall survival was observed. RxFISH technology allowed the description of 27 previously undetected chromosomal abnormalities. Interpretation and Conclusions. Abnormal karyotypes, particularly complex karyotypes, were frequently detected in patients with Sézary's syndrome. Monosomy 10 was the most frequent recurrent cytogenetic marker (73% in abnormal cases). There was a high diversity of chromosomal breakpoints. RxFISH is a useful novel technology for redefining complex karyotypes.