Cerebral amyloid angiopathy and granulomatous angiitis: immunohistochemical study using antibodies to the Alzheimer A4 peptide.

Neuropathologic study of an 82-year-old male who died from massive cerebral hemorrhage showed extensive amyloid angiopathy, with morphologic and immunohistochemical characteristics similar to those observed in Alzheimer's disease, associated with granulomatous angiitis, including the presence of numerous giant cells. Some of the giant cells contained, in their cytoplasm, congophilic material immunoreactive for the Alzheimer A4 peptide, supporting the hypothesis that the granulomatous angiitis may, in part, represent a foreign body reaction to A4 amyloid deposition.