Primary cutaneous T-cell lymphomas (CTCLs) encompass a clinically and biologically heterogeneous group of non-Hodgkin lymphomas (NHLs) defined by clonal proliferation of skin-homing malignant T lymphocytes and natural killer cells. They account for up to 75% to 80% of all cutaneous lymphomas. The current WHO-EORTC classification of cutaneous lymphomas with primary cutaneous manifestations lists 13 entities. The most common subtypes-mycosis fungoides,
Clinical featuresMF is typically a chronic, slowly progressing disease with an indolent evolution. The disease is characterized by the development of patches, plaques or tumors (Figure 1; see Color Figures, page 513). The typical patch is a flat, annular, scaly skin lesion mimicking eczema, psoriasis, or dermatophyte infection. It is often erythematous to violaceous in color and has a predilection for sun-protected areas, including the lower abdomen, upper thighs, buttocks, and female breasts. These initial lesions may spontaneously regress and recur. Patches are highly variable and can give rise to or coexist with plaques, which are raised, palpable skin lesions (Figure 1a and 1b