Abstract: 【Abstract】 Primary cutaneous lymphomas （PCLs） are a heterogeneous group of diseases with distinct clinical manifestations and histopathological features, and their diagnosis and treatment remain challenging. The 5th edition of the WHO Classification of Haematolymphoid Tumours （WHO-HAEM5）, published in 2022, introduced updates to the classification of PCLs, involving multiple subtypes of cutaneous T-cell lymphomas （CTCL） and cutaneous B-cell lymphomas. This update further refines the definition and classification of rare CTCL subtypes and reclassifies Sézary syndrome, removing it from CTCL and categorizing it as a mature T-cell and natural killer cell leukemia. In addition, advances in the molecular genetics of PCLs have been incorporated into the classification of specific subtypes. Based on the major changes in WHO-HAEM5, this article provides an interpretation of the updated classification of PCLs, aiming to provide a reference for clinical practice.

Key words: Lymphoma, Cutaneous lymphomas, Lymphoma, T-Cell, cutaneous, Lymphoma, B-Cell, WHO-HAEM5, Classification interpretation