Leukoencephalopathy in childhood leukemia.

A 14-year-old boy survived for 7 years after the initial diagnosis and treatment of acute lymphocytic leukemia. Neurologic deterioration occured repeatedly throughout his complicated clinical course but it was most severe and only partially reversible following orally administered pyrimethamine. The neuropathologic lesions were distinctive and included a diffuse reactive astrocytosis, axonal degeneration, status spongiosis, circumscribed foci of demyelination and coagulative necrosis, and mural thickening with luminal narrowing of microcirculatory vessels. This collection of findings represents the leukoencephalopathy of childhood leukemia that we and others believe results in large part from the combined effects of cranial irradiation and chemotherapy. The role of folic acid antagonists, namely methotrexate and pyrimethamine, are particularly noteworthy in this regard.