Diagnostic tools in mycosis fungoides.

Cutaneous T-cell lymphomas (CTCL) represent clonal proliferations of neoplastic skin homing T-cells. Within the group of primary CTCL, mycosis fungoides (MF) is the most common entity, affecting the skin as a primary site. MF initially presents in the skin with a slow indolent course of a characteristic stepwise progression from patches to plaques and tumors accompanied by distinctive histological changes. Routine diagnosis is based on these clinical and histological features. However, due to similarities with benign lymphoproliferative or reactive skin diseases, especially at the initial presentation of the disease, diagnosis can be difficult. Although the etiology of mycosis fungoides is still unknown, important insights have been gained in the immunological and genetic perturbations, which are associated with the disease. In the last years the emergence of molecular genetic techniques allowing to analyze the clonality status in lymphocytic infiltrates, has provided new tools with the potential to increase the accuracy of diagnosis, staging and therefore stage-adapted treatment. Nevertheless, it is important to notice that some limitations restrict the predictive value of the results obtained by these analyses. Diagnostic tool of MF, including clinical, histo- and immunohistological findings as well as molecular genetic analysis will be covered in this review.