Development of meningeal leukemia (L1210) during treatment of subcutaneously inoculated mice with methotrexate

that L1210 leukemia inoculated subcutaneously into DBA/2 male mice would rapidly spread to many organs and tissues but that only a few focal leukemic deposits would be found in the dura or arachnoid at the time the animals died. Although leukemic cells circulated through cerebral blood vessels for several days prior to the death of the animal, they did not infiltrate directly into the tissues of the brain or spinal cord or grow diffusely in the arachnoid. Thus diffuse meningeal leukemia was not established at the time the subcutaneously inoculated mice died.' Since a few leukemic cells that appeared to infiltrate directly from adjacent dura were occasionally seen in the subarachnoid spaces of these mice, it was considered of interest to determine whether diffuse meningeal leukemia would From the branches of Pathologic Anatomy and Biochemical Pharmacology, National Cancer Institute, of