Primary cutaneous B-cell lymphoma (low-grade, non large cell).

A 43-year-old man presented with erythematous, indurated plaques on the scalp in the setting of a 16-year history of recurrent cutaneous tumors of the head and trunk. Clinical and histopathologic findings were consistent with a diagnosis of primary cutaneous B-cell lymphoma. Laboratory data and computed tomography imaging of the chest, abdomen, and pelvis failed to show an associated systemic lymphoma. Primary cutaneous B-cell lymphomas are a heterogenous group of lymphomas that primarily involve the skin but have variable clinical, histopathologic, and immunologic phenotypes. Successful treatment for most localized subtypes consists of surgical excision and radiation therapy. Rituximab, a chimeric monoclonal antibody that binds the B-cell-specific antigen CD20, has shown promise in treating a number of primary cutaneous B-cell lymphomas.