WHO-EORTC Classification of Primary Cutaneous Lymphomas:Updates and Interpretation

Primary cutaneous lymphomas (PCL) are a group of non-Hodgkin's lymphomas that are presented with specific clinical manifestations and histopathological characteristics. The classification of PCL published by World Health Organization-European Organization for Research and Treatment of Cancer (WHO-EORTC) in 2005 was the important diagnostic criteria and classification basis for cutaneous lymphomas. With research progression, WHO-EORTC updated the classification of PCL in 2018, adding three subtypes of PCL, namely, chronic active Epstein Barr virus (EBV) infection, primary cutaneous acral CD8⁺ T-cell lymphoma, and EBV-positive mucocutaneous ulcer. Besides, some subtypes of PCL were revised, including lymphomatoid papulosis, primary cutaneous marginal zone lymphoma, and primary cutaneous CD4⁺ small/medium T cell lymphoproliferative disease. This article interprets the update of WHO-EORTC classification of PCL.