Delayed reversible methotrexate-induced leucoencephalopathy in a four-year-old child with acute lymphoblastic leukemia

Intravenous/intrathecal methotrexate (MTX) has been implicated as a major cause of treatment-related neurotoxicity particularly leukoencephalopathy in children with hematological malignancy. We report a 4-year-old boy who presented with apathy and aphasia for 1 day while on the maintenance-phase chemotherapy according to MCP 841 protocol. MRI of brain revealed bilateral symmetrical FLAIR hyperintensities in caudate and putaminal region with FLAIR hypersignal in subcortical U-fiber in left frontal lobe consistent with MTX-induced toxic leucoencephalopathy. There was spontaneous resolution of symptoms within 1 week of onset. So, in Pre-B acute lymphoblastic leukemia patients with subtle neurological deficit, this diagnosis should be kept in mind and further treatment with MTX should be carefully decided.