Cutaneous lymphomas—An update 2019

Primary cutaneous lymphomas (CL) are the second most common form of extranodal lymphomas. Cutaneous T‐cell lymphomas represent the majority. They are classified according to the WHO classification 2017 and the updated WHO‐EORTC 2018 published in the fourth edition of the WHO classification for Skin Tumors monograph. Primary cutaneous acral CD8+ T‐cell lymphoma and EBV‐positive mucocutaneous ulcer have been listed as new provisional entities. Moreover, the histological and genetic spectrum of lymphomatoid papulosis has been expanded. Recently, prognostic subtypes were delineated for some entities and subtypes of CL such as folliculotropic mycosis fungoides and marginal zone lymphoma. Since CL show overlapping histological features, clinico‐pathological correlation is of outmost importance for the diagnosis. Recent studies revealed new biomarkers and genetic alterations underlying the pathogenesis of CL. Moreover, targeted therapies have widened the treatment options particularly for aggressive lymphomas.