Abstract: 【Abstract】 Mycosis fungoides（MF）is the most common subtype of primary cutaneous T-cell lymphoma, and its pathogenesis remains unclear. Recent studies have uncovered high-frequency chromosomal copy number variations in MF, such as gain of chromosomes7q,1q,17q and loss of 9p21,10q,17p, which lead to the gain of proto-oncogenes and loss of tumor suppressor genes, and finally result in tumor development and progression. Moreover, low-frequency single-nucleotide variants have been found in MF, and these mutated genes are mostly enriched in the pathways associated with cell cycle regulation, cell apoptosis, chromatin remodeling as well as T cell activation. Gene-fusion variation is rarely reported in MF. In addition, large cell transformation may occur in some MF cases, and often indicates poor prognoses such as disease progression and drug resistance. In conclusion, MF is a complex disease with highly molecular genetic heterogeneity, and more extensive and intensive researches on its pathogenesis are needed in the future.

Key words: Mycosis fungoides, Genomic structural variation, Polymorphism, single nucleotide, Gene fusion, Comparative genomic hybridization, Large-cell transformation