Studies on the Histopathology of Temporal Arteritis.

Aims: The aim of this paper was to identify the location and to grade the severity of most significant inflammation within positive temporal artery biopsies along with other key clinical and histologic characteristics.

Methods: Charts and pathology slides for 70 patients diagnosed with temporal arteritis at the University of Wisconsin (UW) Hospital and Clinics from 1989 to 2015 were reviewed. A subset of 48 specimens was immunostained for CD68 and graded on a scale from 0 to +++; the location of staining was recorded.

Results: The most severe granulomatous inflammation was in the media and adventitia in 13% (9/70) of the biopsies; the remaining had uniform full thickness inflammation. Of the slides that were stained with CD68, 94% (45/48) were positive. In 42% (19/45), the stained cells were found mainly in the muscularis and adventitia. Seven percent (3/45) of the slides had staining solely around the internal elastic lamina, and 2% (1/45) had staining limited to the intima.

Conclusions: With a few exceptions, granulomatous inflammation in positive temporal artery biopsies is most evident at the media and adventitia or is uniform throughout the layers of the artery. Our study lends support to the theory that the muscularis and adventitia may play an inciting role in the pathogenesis of temporal arteritis.