Indolent primary cutaneous B-cell lymphoma

Indolent primary cutaneous B-cell lymphoma (PCBCL) refers to a group of non-Hodgkin lymphomas that originate in the skin without evidence of extracutaneous disease at the time of diagnosis and follow a characteristically slow, favorable clinical course. This category primarily includes two subtypes: primary cutaneous marginal zone lymphoma (PCMZL) and primary cutaneous follicle center lymphoma (PCFCL). These lymphomas arise from B-lymphocytes in the skin and typically present as solitary or localized reddish-to-violaceous papules, plaques, or nodules, most commonly on the trunk, head, or extremities. The lesions are usually painless and may slowly enlarge over months to years. Unlike aggressive B-cell lymphomas, indolent PCBCLs have an excellent prognosis with 5-year survival rates exceeding 95%. The disease primarily affects the skin (integumentary system) and the immune system. Patients generally do not experience systemic symptoms such as fever, night sweats, or weight loss (so-called B-symptoms), which distinguishes indolent forms from more aggressive lymphoma subtypes. Diagnosis requires skin biopsy with histopathological examination, immunohistochemistry, and staging workup to exclude systemic lymphoma involvement. In some cases, an association with Borrelia burgdorferi infection has been reported, particularly in European populations with PCMZL. Treatment depends on the extent of disease. Localized lesions are often managed with local radiation therapy, surgical excision, or a watch-and-wait approach. For multifocal or recurrent disease, options include intralesional or systemic rituximab (an anti-CD20 monoclonal antibody), topical corticosteroids, or other immunotherapies. Although relapses are common, they are typically confined to the skin and do not significantly affect overall survival. Systemic chemotherapy is rarely required and is generally reserved for the uncommon cases that show progression to extracutaneous sites.

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