Mycosis fungoides-clinical and histopathologic features, differential diagnosis, and treatment.

Mycosis fungoides (MF) is the most common type of cutaneous lymphoma. The term MF should be used only for the classical presentation of the disease characterized by the evolution of patches, plaques, and tumors or for variants showing a similar clinical course. MF is divided into 3 clinical phases: patch, plaque, and tumor stage, and the clinical course is usually protracted over years or decades. Histopathologically, MF is characterized by an epidermotropic infiltrate of T lymphocytes that displays in most cases a helper phenotype. Cytotoxic variants are well described and do not have specific clinical, histopathological, or prognostic features. MF should be differentiated from other cutaneous epidermotropic lymphomas and from many inflammatory dermatoses with some similar clinicopathological features. The therapy of MF is planned mainly according to the stage and extent of the disease. In early phases, nonaggressive options represent the first-line strategy (eg, local corticosteroids, psoralen, and ultraviolet A [UV-A] irradiation, etc.). In patients with advanced disease, good results with potential for cure have been obtained with allogeneic stem cell transplantation, but toxicity is a serious limiting factor for this treatment. Conventional systemic chemotherapy and single-agent chemotherapy (eg, gemcitabine) give usually good results in advanced MF, but recurrences are the rule. Monoclonal antibodies directed against cluster of differentiation (CD)52 (alemtuzumab), CD30 (brentuximab vedotin), and chemokine receptor 4 (CCR4; mogamulizumab), as well as several other experimental therapies, have shown promising results and represent a valid alternative.