Diffuse large B-cell lymphoma arising independently to lymphoplasmacytic lymphoma: a case of two lymphomas.

Richter's syndrome occurs in 5-10% of patients with chronic lymphocytic leukemia, either by transformation of the primary neoplastic lymphocyte, or as a distinct B-cell neoplasm. We report a Japanese patient with lymphoplasmacytic lymphoma in whom a diffuse large B-cell lymphoma developed after treatment with rituximab. Molecular examination on immunoglobulin VH genes revealed that the lymphomas had arisen in two separate clones. We reviewed clinical case reports in literature, and found 30-40% of cases with Richter's syndrome and composite lymphoma had a second B-cell lymphoma of a different origin.