A Case of Leukoencephalopathy Secondary to Methotrexate Toxicity.

Methotrexate (MTX) has known toxicities affecting the kidneys, mucous membranes, liver, lungs, and nervous system. Rarely does a patient take large amounts of MTX, as attempts are made to avoid these toxicities. This case presents a patient who ingested seven weeks' worth of MTX in one week and developed neurotoxicity, with MRI showing subacute infarcts in the right frontal lobe, right parietal, and occipital lobes in the right middle cerebral artery watershed distribution. Prompt leucovorin therapy improved symptoms of altered mental status. This case highlights the importance of accurate prescription instructions and details the neurotoxicity that can occur with high MTX ingestion.