Figure 5 .

(A) Histological findings in the wall of a giant cell arteritis. Wall thickening is mainly due to myofibroblastic proliferation of the intima, with a minimal exudate consisting of lymphocytes and plasma cells. The media is distorted by the granulomatous process, which extends into the adventitia. In the latter, a minimal fibrosis is present. (B)  The media of the artery shows a layer of giant cells on its inner aspect, the site of the inner elastic membrane, and small fragments of elastic fibers in the cytoplasm of giant cells (arrows). Numerous other inflammatory cells are seen in the intima wall. The muscular fibers are degenerate, as evidenced by the cytoplasmic vacuoles.