Leukoencephalopathy (leukodystrophy-like diseases) is all of the brain white matter diseases, whether their molecular cause is known or not. It can refer specifically to any of these diseases:
Progressive multifocal leukoencephalopathy
Toxic leukoencephalopathy
Leukoencephalopathy with vanishing white matter
Leukoencephalopathy with neuroaxonal spheroids
Reversible posterior leukoencephalopathy syndrome
Megalencephalic leukoencephalopathy with subcortical cysts. [Source: Wikipedia 
]
