Primary cutaneous B-cell lymphomas.

Cutaneous B-cell lymphomas (CBCL) are the second most common form of primary cutaneous lymphomas. The cutaneous follicle center lymphoma and the cutaneous marginal zone lymphoma (extranodal MALT type lymphoma) account for the vast majority of CBCL and manifest with nodules. These two lymphoma entities have an indolent, slowly progressive course and an excellent prognosis despite a high rate of recurrences. In contrast, cutaneous diffuse large B-cell lymphoma, leg type, and other rare forms of CBCL display an impaired prognosis and therefore require to be treated with multiagent chemotherapy and anti-CD20 monoclonal antibodies in most cases. Clinico-pathologic correlation, histology with immunohistochemical profile and genotyping as well as staging examinations are crucial diagnostic elements in the work-up of CBCL.