Central nervous system expression of a monoclonal paraprotein in a chronic lymphocytic leukemia patient

An unusual complication of chronic lymphocytic leukemia (CLL) is reported. The patient, a 79-year-old man, had a long standing history of CLL, that had been complicated by the development of a Guillain-Barré-like syndrome and a peripheral biclonal gammopathy. The biclonal immunoglobulins identified in the serum were IgM lambda and IgG lambda. The patient's condition progressed and he eventually developed ophthalmologic complications. Cerebrospinal fluid (CSF) obtained during evaluation of his visual dysfunction contained numerous small, mature lymphocytes consistent with the presence of CLL cells in the central nervous system (CNS); immunoperoxidase staining of these cells revealed a monoclonal population. Protein electrophoretic evaluation of the patient's CSF showed a single monoclonal band and immunofixation electrophoresis of the CSF revealed that the immunoglobulin present was IgG lambda. No evidence for the monoclonal IgM paraprotein identified in serum could be appreciated in the CSF by immunofixation. Taken together, these findings strongly implied that there was CNS involvement by the leukemia and this process caused the patient's neurologic symptoms. Furthermore, this study demonstrates that chronic lymphocytic leukemia should also be considered as one of the hematopoietic malignancies associated with monoclonal gammopathies involving the CNS.