Cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA), also known as congophilic angiopathy, is a form of angiopathy in which amyloid comes out of the walls of the blood vessels of the central nervous system. 
The term "congophilic" is used because the amyloid appears red when looked under a microscope when "Congo red" dye is used. The amyloid material is only found in the brain and as such the disease is not related to other forms of amyloidosis.