A new molecular paradigm in mycosis fungoides and Sézary syndrome.

Mycosis Fungoides (MF) and Sézary Syndrome (SS) are clonal proliferations of mature T-cells manifesting as lymphoproliferative disorders in which the neoplastic cells show a strong propensity for skin-homing. While the predominant site of presentation in MF is the skin, the peripheral blood carries a significant tumor burden in Sézary Syndrome such that it resembles a "leukemic" disease. While the genetic basis of these diseases has been studied using different approaches in the previous years, recent genome-wide studies employing massively parallel sequencing techniques now offer new insights into the molecular pathogenesis of these diseases. In this chapter, we discuss the recent findings elucidating the genomic landscape of MF and SS. The pathways targeted by mutational alterations are discussed and a model for understanding the pathogenesis of these diseases is proposed. It is anticipated that prognostic stratification and therapeutic targeting based on mutational signatures will be achieved in the near future based on the improved understanding of the molecular pathogenesis of these diseases.