5-FU multifocal inflammatory leukoencephalopathy and dihydropyrimidine dehydrogenase deficiency

Multifocal inflammatory leukoencephalopathy (MIL) is a cerebral demyelinati ng syndrome that develops after chemotherapy with 5-fluorouracil (5-FU) and levamisole. The authors report a patient who developed MIL after 5-FU admi nistration not in association with levamisole. She was subsequently diagnos ed with partial deficiency of dihydropyrimidine dehydrogenase, an enzyme ne cessary for 5-FU catabolism. The authors suggest that MIL is a direct resul t of 5-FU chemotherapy and that patients with dihydropyrimidine dehydrogena se deficiency are at increased risk for this and other toxic effects of 5-F U.