B-cells are a type of lymphocyte involved in regulating immune responses.

[1]) Since its original definition in 1997, CBCL has been considered to have a varying number of subtypes by the European Organisation for Research and Treatment of Cancer, i.e., EORTC, and World Health Organization, i.e., WHO.

[2] The latest revised classification of CBCL, which was published by EORTC in 2022, lists the following three main subtypes of CBCL (now termed PCBCLPD):[3] Because recent studies had shown that primary cutaneous marginal zone lymphoma, which was formerly classified as a subtype of the MALT lymphomas: a) has a distinct microscopic histology and gene expression profile; b) spreads to extracutaneous tissue in only 4 to 8.5% of cases; c) has a 5 year disease-specific survival in excess of 99% even in patients not receiving aggressive therapy; and d) has pathological findings that overlap the benign cutaneous disorders termed cutaneous lymphoid hyperplasia.

[4] The majority of patients achieve complete remissions following surgery and/or radiation therapy.

[3] Primary cutaneous diffuse large B-cell lymphoma, leg type is an aggressive B-cell lymphoma that is often resistant to therapy and carries a poor prognosis,[5] i.e., they have a 5-year disease-specific survival rate of 43% or 70% depending on whether their cancer cells have or do not have, respectively, inactivating mutations in both of their CDKN2A genes.