Pyrimethamine in prevention of relapses of meningeal leukemia: report of two cases.

Relapses of meningeal leukemia occurred in two children during hematologic remission of acute lymphoblastic leukemia. Treatment of CNS leukemia consisted of radiotherapy and repeated intrathecal injections of methotrexate and cytosine arabinoside. Intrathecal installations of the drugs were accompanied with increasing neurological side effects which seemed to be lifethreatening. To avoid them, repeated courses of pyrimethamine were introduced. No further relapse of meningeal leukemia occurred after pyrimethamine. Hematologic remissions in both children have lasted for over 7 years. All therapy was stopped 16 months ago.