Primary cutaneous lymphoma: the 2018 update of the WHO-EORTC classification

Primary cutaneous lymphomas are a heterogeneous group of cutaneous T-cell lymphomas (CTCL) and cutaneous B-cell lymphomas (CBCL) that present in the skin with no evidence of extracutaneous disease at the time of diagnosis. In the last decade the 2005 WHO-EORTC consensus classification has served as a golden standard for the diagnosis and classification of these conditions. Recently, an updated version of the WHO-EORTC was published. This classification contains several new entities, including primary cutaneous acral CD8+ T-cell lymphoma and EBV-positive mucocutaneous ulcer, while other conditions were slightly modified. Herein, the characteristic features of the different types of CTCL and CBCL are presented, differences with previous classification schemes discussed and the results of more recent molecular studies with clinical implications for these conditions reviewed. In addition, an update of the frequency and survival of the different types of primary cutaneous lymphomas is provided.