Isolated chloromas (granulocytic sarcomas) are rare tumors. Chloromas are masses composed of immature granulocytic cells. Granulocytic sarcoma occurs primarily in patients with acute myelogenous leukemia and may also arise in patients with other myeloproliferative disorders, but rarely in patients with acute lymphoblastic leukemia (ALL). When dural-based, granulocytic sarcoma may be indistinguishable from meningioma radiologically. We now describe one patient affected by ALL with isolated granulocytic sarcoma mimicking a falx meningioma as initial CNS relapses. These unusual clinical manifestation and radiological finding in ALL should be considered as recurrence of leukemia. Early detection and antileukemic treatment of granulocytic sarcoma are necessarily important for favorable prognosis.