A 51-year-old woman developed subacute progressive gait and cognitive difficulties, with depression and anxiety. She had psychomotor slowing, axial rigidity, fixed dystonic posturing of right hand and symmetrical generalised bradykinesia. MR brain scan identified bilateral multifocal non-enhancing high signal intensity in the frontal subcortical and periventricular areas, with corpus callosal thinning and areas of paraventricular diffusion restriction, suggesting an adult-onset leukodystrophy. Genetic analysis identified a heterogenous pathogenic variant in the colony-stimulating factor 1 receptor (CSF1R) causing this autosomal dominant leukoencephalopathy (OMIM 221820). The patient was unusual in having a CSF1R-related leukoencephalopathy without a relevant family history.