Complete remission of a primary cutaneous B-cell lymphoma of the lower leg by first-line monotherapy with the CD20-antibody rituximab

Background: Rituximab is a genetically engineered antibody recognizing the CD20 antigen known to be expressed by more than 95% of B-cell lymphomas. Recently the antibody has been approved for routine administration in primary extracutaneous, treatment-refractory or relapsed low-grade, follicular non-Hodgkin B-cell lymphomas. With regard to the pathogenetically related primary cutaneous lymphomas, the socalled large B-cell lymphoma of the leg represents a distinct, but rare subentity. In an 89-year-old, multimorbid patient who was affected by such a non-resectable CD20+ large B-cell lymphoma limited to the skin of both lower legs, rituximab was used as a first-line monotherapy in order to avoid local or systemic toxicities inevitably linked to conventional treatment modalities, i.e., radio- or chemotherapy. Methods: Rituximab was administered at a dosage of 375 mg/m(2) i.v. eight times in weekly intervals. As a premedication we used prednisolone 150 mg i.v. as well as loratadine 10 mg p.o. 1 h before each rituximab infusion. Results: The treatment was well tolerated without any adverse reactions, but was accompanied by a mild transient blood eosinophilia. The histologically proven, exophytic, multi-nodular lymphoma showed a substantial regression already at 2 weeks after the onset of the rituximab treatment. At 8 weeks we observed a complete clinical remission which is now stabile for a follow-up period of 6 months without any maintenance therapy. Conclusions: Our case observation demonstrates that an intensified, i.e. eightfold, rituximab application in weekly intervals may be a highly effective, tumor target cell-specific first-line monotherapy in the management of primary cutaneous large B-cell lymphoma of the leg. Given the rareness of the disease, the result as well as the possible contribution of the prednisolone premedication will have to be evaluated in a future, controlled, multi-centre study.