Concomitant Epstein-Barr virus-negative large B-cell lymphoma (Richter syndrome) and Epstein-Barr virus- positive B-cell lymphoproliferation after treatment with fludarabine and cyclophosphamide in a patient with B-cell chronic lymphocytic leukemia.

We report the case of a patient treated with a combination of fludarabine and cyclophosphamide after suffering from B-cell chronic lymphocytic leukemia for 10 years. Three months after treatment, the patient presented with an unusual association, not previously reported in the literature: Richter syndrome (monotypic Epstein-Barr virus- negative large B-cell lymphoma) with the proliferation of Epstein-Barr virus-positive B cells secreting a polytypic immunoglobulin A. The Epstein-Barr virus-positive lymphoproliferation can be accounted for by the type of immunosuppression induced by the treatment.