Primary cutaneous large B-cell lymphoma of the legs: a distinct clinical pathologic entity treated with CD20 monoclonal antibody (rituximab).

Primary cutaneous large B-cell lymphoma of the legs (PCLBLL) is most commonly diagnosed in the elderly, and is generally confined to the lower parts of one or sometimes both legs. Despite treatment with radiotherapy, relapses and extracutaneous involvement can occur, and unlike other low-grade cutaneous-B-cell non-Hodgkin's lymphomas (NHLs), the prognosis is variable, with an estimated 5-year survival rate of 58%. This report describes the case of an 81-year-old man who was diagnosed with PCLBLL. Staging evaluation did not reveal NHL elsewhere. The patient declined recommendations to receive cytotoxic chemotherapy. Instead, he was treated with anti-CD20 monoclonal therapy (rituximab) and his cutaneous lesions completely regressed during a 16-week period. This report suggests that rituximab is a therapeutic option for those patients with PCLBLL who may not be good candidates to receive radiation therapy or chemotherapy. Long-term follow-up and greater experience with rituximab in a variety of clinical settings will ultimately determine the appropriate role of this costly, but relatively safe, antibody-based therapy for CD20+ expressing NHLs.