Mycosis Fungoides and Sézary Syndrome: Microenvironment and Cancer Progression

SIMPLE SUMMARY: The surrounding cells of the tumor tissue are called microenvironment, and they may contribute to disease progression and/or antitumor immune response. Much has been learned about the microenvironment of mycosis fungoides and Sézary syndrome over the past decades and how it is affected by treatments. This review summarizes the recent advances in the field. ABSTRACT: Mycosis fungoides and Sézary syndrome are epidermotropic cutaneous lymphomas, and both of them are rare diseases. Mycosis fungoides is the most frequent primary cutaneous lymphoma. In about 25% of patients with mycosis fungoides, the disease may progress to higher stages. The pathogenesis and risk factors of progression in mycosis fungoides and Sézary syndrome are not yet fully understood. Previous works have investigated inter- and intrapatient tumor cell heterogeneity. Here, we overview the role of the tumor microenvironment of mycosis fungoides and Sézary syndrome by describing its key components and functions. Emphasis is put on the role of the microenvironment in promoting tumor growth or antitumor immune response, as well as possible therapeutic targets. We focus on recent advances in the field and point out treatment-related alterations of the microenvironment. Deciphering the tumor microenvironment may help to develop strategies that lead to long-term disease control and cure.