[Cerebromeningeal location of chronic lymphoid leukemia. Rapid immunochemical diagnosis and complete remission by intrathecal chemotherapy].

Central nervous system (CNS) involvement is a rare complication of chronic lymphoid leukaemia (CLL). The occurrence of lymphocytic meningitis in the course of CLL suggests either CNS involvement by the leukaemic process or infection (especially tuberculosis) related to continuous immunodepression. We report a case of CLL in which leukaemic cells had surface IgM and produced IgM kappa without significant depression of other immunoglobulins. When the patient developed meningitis, measurement of serum and CSF albumin IgG and IgM levels showed that 88% of CSF IgM resulted from local synthesis, while 70% of CSF IgG resulted from serum transsudation. These results suggest that a large number of neuromeningeal lymphoid cells produce the same class of IgM as leukaemic cells and therefore constitute a localization of the disease. Complete remission of the meningitis by intrathecal anti-leukaemic chemotherapy confirmed this hypothesis.