Unilateral optic nerve leukemic infiltration with sudden vision loss heralding a systemic relapse of acute lymphoblastic leukemia

We describe a 21-year-old patient with acute lymphoblastic leukemia (ALL) who achieved complete remission after induction, consolidation chemotherapy and central nervous system prophylaxis with intrathecal methotrexate and cranial irradiation. He developed a relapse of ALL 6 months after remission. This presented as isolated optic nerve infiltration with leukemic cells and sudden loss of ipsilateral vision prior to systemic relapse. Subsequent surgical intervention, salvage chemoradiotherapy and further allogeneic stem cell transplantation did not induce disease remission or restore his visual acuity.