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PRIMARY CUTANEOUS B-CELL LYMPHOMA
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The World Health Organization and European Organization for Research and Treatment of Cancer joint classification has classified primary cutaneous B-cell lymphomas (PCBCL) into three distinct main entities: primary cutaneous follicle-center lymphoma (PCFCL), primary cutaneous marginal zone lymphoma (PCMZL), and primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL, leg type). The latter subtype carries a worse prognosis. The most important prognostic determinant is disease histopathology. Furthermore, it is important to differentiate PCBCLs from their systemic counterparts with appropriate systemic work-up including imaging such as a whole body PET/CT, complete blood count, chemistries, and peripheral blood flow cytometry. These are rare diseases and large clinical trials are lacking. Most therapies discussed are based on case series or case reports. Therapeutic options include localized radiation therapy, systemic anti-CD20 monoclonal antibody therapy, and multi-agent chemotherapy. Of note, PCMZL and PCFCL with extracutaneous involvement should be treated as nodal marginal zone lymphoma and follicular lymphoma, respectively. See Table 117-1.
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Levels of evidence are based on the Journal of the American Academy of Dermatology guidelines: level IA evidence includes evidence from meta-analysis of randomized controlled trials; level ...