[Primary cutaneous B-cell lymphomas-an overview of established and novel aspects]

Primary cutaneous B‑cell lymphomas (PCBCL) belong to the group of extranodal non-Hodgkin lymphomas and by definition only manifest on the skin at the time of diagnosis. These lymphomas can be broadly classified into indolent and aggressive subtypes. Indolent PCBCLs include primary cutaneous marginal zone lymphoma, primary cutaneous follicular B‑cell lymphoma and Epstein-Barr virus-positive mucocutaneous ulcer, which present solitary or multifocal lesions and are associated with a favorable prognosis. Treatment usually involves excision or radiotherapy, although a watch-and-wait concept can also be discussed. Conversely, aggressive PCBCLs, such as primary cutaneous diffuse large B‑cell lymphoma, leg type, and primary cutaneous intravascular large B‑cell lymphoma, carry a high risk of systemic dissemination. Consequently, they require systemic treatment. The standard first-line therapy is typically the R‑CHOP regimen, which may be supplemented with radiotherapy.