[Richter's syndrome. Presentation of a rare variant with regression of chronic lymphatic leukemia and review of the literature].

The incidence of a lymphoreticular system malignancy in patients with chronic lymphocytic leukemia (CLL), Richter's syndrome (RS), is 3.3 to 10.6%. In 89 cases in the literature, the second neoplasm was either reticulum cell sarcoma or large cell diffuse histiocytic lymphoma (DHL), and there were 61 cases of Hodgkin's disease (HD). In a few cases the lymphoma was simultaneously diagnosed, for other cases an association with preexisting CLL was reported. Appearance of lymphoma was associated with leukemia regression for only 4 patients with DHL and 3 with HD. We report one case of B-lymphocyte CLL with macroglobulinemia, treated with melphalan and prednisone, in which DHL developed and the hematologic and histologic signs of CLL and of paraproteinemia remissed. Such patients might constitute a subgroup or a variant of RS. Since the non-Hodgkin malignant lymphomas (NHML) are considered to be monoclonal neoplastic expansion of the B-cell or T-cell lymphocytes, and since in some cases it has been proved that the proliferative cell clone was the same as that of the initial lymphoproliferative disease, RS could be a dedifferentiation or a transformation of CLL, resulting in an aggressive clinical course. The inclusion in this syndrome of CLL cases associated with HD is still controversial. Many of these cases could be giant cell pleomorphic lymphomas, while, on the contrary, in typical cases this association might be merely fortuitous.