Past, present and future of cutaneous lymphomas.

Primary cutaneous lymphomas represent a broad group of diseases with different clinical, histopathological, phenotypic, molecular, and prognostic features. All cutaneous lymphomas share the same tropism of neoplastic lymphocytes for the skin, but precise classification is paramount for proper management of the patients. Primary cutaneous lymphomas are classified according to the schemes proposed by the European Organization for Research and Treatment of Cancer (EORTC)-Cutaneous Lymphomas Task Force together with the World Health Organization (WHO) in 2005, and the WHO classification of 2008 with the 2016 update. The recognition of organ-based lymphomas, including cutaneous lymphomas, reflects a shift in the approach to lymphoproliferative disorders, and represents one of the major advances in the WHO classification of hematological tumors. Future studies should be aimed at shedding light on the many grey areas of cutaneous lymphomas (particularly the diagnosis and nomenclature of early mycosis fungoides and variants), and at gathering more data on the disorders that are still listed as provisional entities in the WHO classification.