In the field of leukoaraiosis, the identification of CADASIL and its link to Notch 3 mutation has shed light on the pathogenesis of white matter (WM) abnormalities related to small-vessel disease. Since 1993, its systemic vascular involvement allows skin biopsy diagnosis and research on tissues before postmortem examination. We received 160 skin biopsies from patients presenting subcortical dementia, recurrent strokes, behavioral disturbances or migraines, and suspected CADASIL. Almost all the patients lacked the well-known vascular risk factors. The ultrastructural study was systematically carried out looking at the vessel walls and the other components found in skin. In a third, we found endothelial changes, destruction of vascular smooth muscle cells (VSMCs), and characteristic granular osmiophilic material (GOM). In these cases, the genetic analysis confirmed the Notch 3 mutation. Curiously, the skin biopsies from the other two thirds presented marked alterations within the vessel walls. Such changes included destruction of VSMCs, lack of GOM, and replacement of these cells by an extracellular matrix. Frequently, we noticed endothelial pathological changes as well as other tissue impairments. By now, we are able to describe eight different groups of lesions according to either the prevalence of a lesion or the association of different lesions. The skin biopsy ultrastructural study seems to be highly informative given that we can observe vessel lesions and association of impairments in various tissues that might, in part, explain the brain vessel involvement and then the leukoaraiosis and probably some clinical symptoms. Moreover, these vessel lesions often belonged to young people (30-50 years old), and many of them seemed to run in families. These new data associated with early onset of clinical symptoms and leukoaraiosis would be extremely valuable in clarifying the wide field of leucoencephalopathy and might provide genetic research with new issues.