Carmofur, a derivative of 5-fluorouracil, has recently been noted to h
ave an infrequent but serious association with leukoencephalopathy. To
our knowledge, there has been no report of early MRI findings in this
leukoencephalopathy. We describe a case in which diffuse high signal
intensity of the entire cerebral white matter, including the corpus ca
llosum, was seen on T2-weighted magnetic resonance images. Although si
milar findings can be seen in many other diseases, carmofur-induced le
ukoencephalopathy should be suspected in a patient treated with carmof
ur. It is important to know the clinical and MRI characteristics of th
is condition, for early diagnosis and better prognosis.