ATROPHY OF THE AORTIC MEDIA IN GIANT-CELL ARTERITIS

Aortic tissue from seven patients with giant cell arteritis (GCA) was investigated using light microscopy and immunocytochemistry. Four surg ical cases and three autopsy cases were included. All the specimens di splayed a severe reduction in the size and number of media smooth musc le cells immunopositive for alpha-smooth muscle actin (alpha-SMA). A s ubtotal loss of alpha-SMA-positive cells was seen in non-inflamed medi a tissue, continuing gradually towards multiple calcified acellular le sions totally devoid of alpha-SMA immunoreactivity. There was a slight to moderate granulomatous inflammatory reaction in the tissue surroun ding part of the acellular lesions. Foreign body giant cell reaction a nd elastin degradation were found at the ends of the acellular calcifi ed areas. The present findings indicate that the atrophy and the loss of alpha-SMA-positive cells in the aortic media in GCA is primary, and that the granulomatous reaction is secondary and directed against atr ophic calcified media tissue.