Isolated bone relapse in a child with acute lymphoblastic leukemia off-therapy

Osseous relapse, as distinct from bone marrow relapse, is possible during treatment of childhood leukemia. The authors have observed an isolated leukemic bone lesion in an 8-year-old boy in complete bone marrow remission after a second full course of chemotherapy for a testicular leukemic localization. The radiological signs in our case are peculiar because a small bone of the foot (right talus) showed an increased density instead of rarefaction; histological examination demonstrated leukemic bone infiltration. Local radiotherapy (2400 cGy) was given and multidmg induction and maintenance for one year. Two years after the histological diagnosis the child is still in complete remission. This observation suggests that structural bone may be a sancturay site for leukemic cells.