Cutaneous T-cell lymphoma: Review with emphasis on immunophatogenesis

Abstract

The term cutaneous T-cell lymphoma (CTCL) refers to several diseases that have in common the presence of a malignant T-cell clone with involvement of the skin. Mycosis fungoides (MF) is the most common form of CTCL, followed by the Sèzary syndrome (SS). The cause of mycosis fungoides is unknown. Immunophenotype of most cases of MF is made up by memory T cells CD3⁺CD4⁺CD45RO⁺CLA⁺CD8^-. Malignant T CD4⁺ lymphocytes migrate to the epidermis and localize around Langerhans cells. In SS, cells loose their epidermotropism and extensively infiltrate the dermis, blood and other tissues. These cells present a predominant immunophenotype of neoplasic T cells CD3⁺CD4⁺CD8^-CD7^-CD26^-CD158k⁺CD94^-. The Th2 profile and the supression of Th1 responses are two critical factors in the progression of the disease. Alterations in the immune regulation in CTCL have not been thoroughly evaluated. A better understanding of T-cell function and of the immunobiology of CTCL would allow to improve the prognosis, therapy and follow-up of patients with these neoplasias.