Malignant lymphoma supervening in chronic lymphocytic leukemia and related disorders. Richter's syndrome: a study of 25 cases.

Richter's syndrome (RS) has been defined as "histiocytic" lymphoma (HL) or Hodgkin's disease (HD) supervening in the course of chronic lymphocytic leukemia (CLL) and related disorders. The clinical, histologic, and immunologic findings in 25 cases (11 women, 14 men) of RS are presented. The initial diagnosis was CLL in 19 cases, diffuse well-differentiated lymphocytic lymphoma in 2 cases, and Waldenstrom's macroglobulinemia in 4 cases. The interval between the initial diagnosis and that of RS ranged from 0 (two cases) to 120 months (median 49 months). At the time of diagnosis of RS, the initial lymphoproliferative disorder was in apparent complete remission in only two cases. The lymphoma was disseminated in at least 18 cases. The overall median survival was four months, but complete remission was achieved in six cases and has been maintained for 15 to 77 months. In four of these six cases, the RS was localized. The histologic diagnosis of HD was made in only two cases. In the other 23 cases, the diagnosis was HL, but in five of these cases, the proliferation was heterogeneous and was considered as an early aspect of HL. Immunologic studies of lymph node cell suspensions were performed in seven cases. In all cases, the B-lymphocytic origin of the lymphoma cells could be ascertained. Detailed studies in four cases showed that lymphoma cells carried SIg of the same isotype and light chain type as that of SIg detected on CLL cells or of monoclonal serum Ig. In these cases, the lymphoma was actually related to the initial B-cell chronic lymphoid disease.