High incidence of meningeal leukemia in lymphoid blast crisis of chronic myelogenous leukemia.

Fifteen patients with lymphoid blast crisis of chronic myelogenous leukemia (LyBC-CML) and five patients with acute lymphoblastic leukemia converting to Philadelphia-positive (Ph+) chronic myeloid leukemia (ALL Ph + CML) were followed. Seven of 15 (46.7%) LyBC-CML patients developed meningeal leukemia within a median period of 6 months (range 2-11 months), while there was no medullary relapse. Five of these responded well to triple intrathecal therapy. In the ALL Ph + CML patients, in spite of central nervous system (CNS) prophylaxis with IT MTX and 18 Gy cranial radiation, two of five patients (40%) experienced meningeal leukemia, one isolated and the other with medullary relapse. The data confirm that LyBC-CML patients experience a high incidence of meningeal leukemia. The role of CNS prophylaxis is not very clear, but its use may delay development and reduce morbidity due to CNS disease.