Juvenile xanthogranuloma (JXG) is a rare benign disorder which in the classification of non-Langerhans cell histiocytosis, its etiology and pathogenesis is still unclear. JXG is generally characterized by solitary or multiple cutaneous nodules which resolve spontaneously over a few years; however it is uncommonly possible to present extra-cutaneous disorder and progress symptomatic systemic disorder through involving multiple organs. Systemic JXG is occasionally associated with morbidity and may require chemotherapy with LCH-based regimens. Although the relation between JXG and lymphocytic leukemia is unknown, we experienced unusual case of systemic JXG involving bone marrow and several bones when is occurred during acute lymphocytic leukemia treatment. Further study is needed to revealed relation between systemic JXG and hematologic malignancies.