The molecular pathogenesis of mycosis fungoides and Sézary syndrome.

Mycosis fungoides (MF) and the Sézary syndrome (Sz) are the two most frequent forms of cutaneous T cell lymphomas (CTCL). Generally the Sz is regarded as a leukemic variant of MF. They are caused by malignant CD4+ T cells, which infiltrate the skin and both diseases proceed in different stages. It has been found in colon carcinoma that cancerogenesis is a sequence of activation of different oncogenes and inactivation of tumor suppressor genes. This finding has initiated efforts to identify the genes that are responsible for the progression of MF and Sz. The development of new screening methods has strongly accelerated this search and many oncogenes and tumor suppressor genes have been identified that may play a role in the progression of both diseases. Changes in the expression of some of these genes are already found at early stages, whereas others become active or inactivated only in later stages. These results will help to search for more specific drugs and lead to a more exact staging that will help to develop effective and personalized treatments of these diseases.