Slowly progressive cystic leukoencephalopathy with megalencephaly in a Japanese boy.

A Japanese boy with megalencephaly and leukoencephalopathy was reported. The clinical characteristics were as follows; slowly progressive megalencephaly starting at 8 months, and motor impairment with ataxia and spasticity, with relatively preserved intelligence and well-controlled epilepsy, and the following MRI findings; diffuse leukoencephalopathy in the supratentorial white matter with cystic subcortical white matter in the temporal tips and the fronto-parietal lobes. This corresponds to vacuolating leukoencephalopathy with megalencephaly, which was recently reported in European countries. In Japan, there were similar case reports previously, however, the patients were diagnosed as having Alexander's disease. It seems that this new leukoencephalopathy must also be seen among Japanese.