Aggressive primary cutaneous B-cell lymphoma

Aggressive primary cutaneous B-cell lymphoma is a rare group of non-Hodgkin lymphomas that originate in the skin without evidence of extracutaneous disease at the time of diagnosis. This category primarily includes primary cutaneous diffuse large B-cell lymphoma, leg type (PCDLBCL-LT), which is the most common aggressive subtype, and other rare aggressive variants. These lymphomas are characterized by the rapid development of red or violaceous skin nodules or tumors, most frequently appearing on the lower legs, though they can occur at other body sites. The disease predominantly affects elderly individuals, with a higher incidence in women. Unlike indolent primary cutaneous B-cell lymphomas, aggressive forms have a tendency to disseminate to extracutaneous sites, including lymph nodes and internal organs, and carry a significantly worse prognosis. The malignant B-cells in aggressive primary cutaneous B-cell lymphoma typically express markers such as BCL2, MUM1/IRF4, and FOXP1, reflecting a non-germinal center (activated B-cell) phenotype. Patients may present with solitary or multiple rapidly growing skin lesions that can ulcerate. Systemic symptoms such as fever, night sweats, and weight loss (B symptoms) may occasionally be present. Diagnosis requires skin biopsy with immunohistochemical analysis, and staging workup including imaging studies is essential to confirm the disease is limited to the skin at presentation. Treatment typically involves R-CHOP (rituximab combined with cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy, which is the standard first-line regimen for aggressive subtypes. Radiation therapy may be used for localized disease or as consolidation. Despite treatment, relapse rates are relatively high, particularly for PCDLBCL-LT, with a 5-year survival rate estimated at approximately 50-60%. Novel targeted therapies, including lenalidomide and ibrutinib, are being investigated for relapsed or refractory cases. Close follow-up is essential due to the risk of cutaneous and systemic recurrence.

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