A Case of Diffuse Leukoencephalopathy Following Low Dose Intravenous Methotrexate Therapy

ABSTRACT

Diffuse leukoencephalopathy is a well-known complication of methotrexate in intrathecal or high dose intravenous administration, especially when it is combined with cranial radiation therapy. However, low dose intravenous methotrexate induced leukoencephalopathy has not been reported previously. A 46-year-old female was administered intravenous methotrexate and 5-fluorouracil with oral cyclophosphamide after a modified radical mastectomy for breast cancer. After six cycles of chemotherapy, she developed rapidly progressing dementia and upper motor neuron signs. Brain MRI showed bilaterally symmetric white matter lesion without gadolinium enhancement. Laboratory investiga-tion showed no evidence of brain metastasis. This case suggests that low dose intravenous methotrexate can induce dif-fuse leukoencephalopathy.