Granulomatous reaction to Bruch's membrane in age-related macular degeneration.

The histopathologic features of a granulomatous reaction in one eye of a patient with neovascular age-related macular degeneration are presented. Multiple multinucleated giant cells were found in intimate association with Bruch's membrane and at the margin of Bruch's membrane defects. Multinucleated giant cells appear to participate in the breakdown of Bruch's membrane and, together with diffuse disease of the retinal pigment epithelium and changes in the physicochemical properties of Bruch's membrane, may provide angiogenic stimulus for choroidal neovascularization in age-related macular degeneration.