Figure 3.

Representative histopathologic findings in the retina, brain and kidney. Microscopic examination of various organs shows a characteristic vasculopathy. The vessels of the inner layers of the retina often demonstrate damage to the walls with occasional deposition of amorphous material [arrow (A)] or thickened collagenous walls. H&E = haematoxylin and eosin stain; Vit = vitreous; NL = nerve fibre layer; GCL = ganglion cell layer; IPL = inner plexiform layer; INL = inner nuclear layer; OPL = outer plexiform layer. The brain also shows a prominent vasculopathy in the white matter, most often adjacent to and in sites of coagulation necrosis. Small to medium sized vessels demonstrate vascular wall thickening with varying degrees of luminal narrowing [arrows; (B) haematoxylin and eosin; brain). In some cases, this progresses to a frank fibrinoid necrosis. In areas with extensive white matter ischaemic damage, granular calcifications are particularly evident (dark blue staining in lower left of B). The vasculopathy may result in luminal obliteration leading to parenchymal necrosis (C; haematoxylin and eosin; brain). There is concentric collagenous thickening of the vessel walls, mostly involving the medial layer of the vessels (D; Trichrome stain; brain). Ultrastructural examination of affected vessel walls in the brain demonstrates multilaminated basement membranes with duplication of the lamina densa [arrowheads; (E) electron microscopy] in contrast to that found in unaffected regions [arrowhead; (F) electron microscopy]. lum = lumen; EN = endothelial cell. In the kidney, the vasculopathy is manifested by arteriosclerosis [arrow; (G) haematoxylin and eosin] and glomerulosclerosis.