Primary central nervous system lymphoma as a variant of Richter's syndrome in two patients with chronic lymphocytic leukemia.

Primary parenchymal central nervous system (CNS) non-Hodgkin's lymphoma subsequently developed in two patients with chronic lymphocytic leukemia (CLL). These two patients represent what we believe to be the first examples of Richter's syndrome due to primary brain lymphoma. Neither evidence for systemic lymphoma nor of progression of the leukemia was found. We believe that the description of these two cases expands the clinical spectrum in which Richter's syndrome may occur. In patients with CLL, careful attention must be given to neurologic symptoms, particularly those that develop abruptly. Primary CNS lymphoma must enter into the differential diagnosis when a cerebral mass lesion is found in such patients by the appropriate neuro-imaging.