Erythrodermic CTCL: updated clues to diagnosis and treatment

Erythroderma is a rare but severe cutaneous condition characterized from a clinical point of view by a complete involvement (as per definition more than 80% body surface) of the skin surface. Pre-existing dermatoses account for about 70% of erythroderma cases, drug reactions are responsible for erythroderma in about 20%, whilst primary cutaneous T-cell lymphoma (CTCL) constitute less than 10% of and are represented by erythrodermic mycosis fungoides and Sézary syndrome. The challenge in these patients is represented by the identification of the etiological agents or conditions, which is clearly of overwhelming relevance in the clinical management and treatment strategies. In recent years, the development of multiparameter flow-cytometry, which allows to identify specific antigens expressed or not expressed on the surface of atypical lymphoid T-cells, and T-cell molecular biology techniques, which are aimed to identify the presence of a clonal T-cell population in the skin and blood on the basis of the finding of rearrangement of the T-cell receptor, have represented relevant useful tool in the differential diagnosis between benign and lymphomatous erythroderma. Moreover, a better understanding of the immunological and molecular pathways in CTCL disease evolution provided the identification of specific therapeutical targets, as well as the constant improvement in the laboratory techniques lead to the development of new and promising agents in CTCL.