Cutaneous B-cell lymphoma
Cutaneous B-cell lymphomas (CBCL), more recently termed Primary cutaneous B-cell lymphomas and lymphoproliferative disorders (PCBCLPD), are a group of disorders that typically present as skin lesions consisting of proliferating B-cells. B-cells are a type of lymphocyte involved in regulating immune responses.
Source: Wikipedia — Cutaneous B-cell lymphoma (CC BY-SA 4.0)