CSF1R-related Adult-onset Leukoencephalopathy: The First Reported Case in Spain.

Colony-stimulating factor 1 receptor-related adult-onset leukoencephalopathy is a primary microgliopathy characterized by a complex phenotype, which can be easily misdiagnosed with other leukoencephalopathy and neurodegenerative diseases such as frontotemporal dementia. It is estimated to be the most common adult-onset leukodystrophy. Here, we report the case of a 67-year-old man with a history of progressive impairment of behavioral and cognitive functions, including apathy, inhibition, tendency to mutism, and deficits in complex planning skills. Neurological examination revealed pyramidalism in the lower limbs. Brain imaging showed symmetrical confluent frontal leukoencephalopathy, bilateral frontal calcifications, and thinning of the corpus callosum. The diagnosis was confirmed by the identification of a heterozygous pathogenic variant in the colony-stimulating factor 1 receptor. As far as we know, this is the first documented case in Spain. In this paper, we aim to expand on clinical features and underline the importance of brain imaging for the diagnosis of an entity that we consider to be underdiagnosed.