Senile aortic amyloid. Evidence for two distinct forms of localized deposits.

Aortic tissues obtained at autopsy were examined from 84 patients (age, 18-96 years). Amyloid deposits were present in the media in 61 of 63 (97%) of the patients above the age of 50. In addition, intimal amyloid deposits were present in 35% of this group. Intimal amyloid differed from medial amyloid both in its morphologic characteristics and its association with atherosclerosis. An antiserum raised to a low molecular weight protein extracted from amyloid fibrils of the aortic media reacted specifically with medial amyloid but did not react with intimal deposits. Neither type of amyloid reacted with anti-ATTR (Senile systemic amyloid), anti-AANF (isolated atrial amyloid), or antisera to other known forms of amyloid. These findings are consistent with the presence of two separate forms of localized amyloid in the aging aorta.