Background/Purpose: Giant cell arteritis (GCA) is a systemic vasculitis of large and medium-sized arteries mostly reported in Caucasians (CCs) over 50 y.o. There is limited data in the literature on the incidence of GCA in patients of African descent. Here, we review the incidence of GCA based on temporal artery (TA) biopsies in a comparatively large cohort of African-American (AA) patients.

Methods: This is a retrospective chart review of patients (pts) who underwent TA biopsies (TABs) for suspicion of GCA between 1/1/1997 and 1/31/2018 at a tertiary medical center in USA. Cases were identified by searching the pathology database at our institution. Terms used in the search included temporal artery, temporal arteritisa, giant cell arteritis, and borderline arteritis. Self-reported demographics were obtained from the charts. Glass slides from 2 AA pts with a positive pathology report for GCA were reviewed by a pathologist to confirm positivity based on histopathologic features for GCA. Comparisons were made with Fisher Exact Test, using two-tailed test with < 0.05 considered significant.

Results: 200 pts with TABs were identified (Table 1). Of these 30/200 (15%) were AA with a total of 33 TABs (3 bilateral). The median age of diagnosis was 66.5 (range 45-90), and 23/30 (75.66%) were female. Although 2/30 (6.7%) were originally reported as positive for GCA, upon review by the pathologist, one was consistent with small vessel vasculitis with fibrinoid necrosis, and the other did not have histopathologic features of GCA. In contrast, 25/155 (16%) CC pts had positive TABs with a median age of 76 (range 56 – 87) and 98/155 (63.22%) were female.  The remaining 15/200 pts were of other ethnicities of whom 2 had positive TABs. GCA was less frequent in AAs than CCs based on TAB (P=0.0163). Only 3 AAs were seen by a rheumatologist before biopsy as most of the biopsies of AA pts were requested by ophthalmologists, neurologists and primary care physicians. Reasons for biopsy referral among AAs were headache; 24/26 (92%), Scalp tenderness; 9/17 (53%), jaw claudication; 3/13 (23%), and vision loss; 6/21 (28.6%). 14/25 (56%) AA pts had ESR > 50 mm/hr, and 19/22 (86.4%) met 3/5 ACR classification criteria for GCA.

Conclusion: This is one of the largest reported case series in the literature of TA biopsies (TABs) performed in patients of African descent in a single institution in North America. Pathological features of GCA were not present in any TABs in this cohort of 30 African-American (AA) pts.  Our data correlates with the clinical observation that GCA usually presents in Caucasians and is rare in AAs.  The suspicion and diagnosis of GCA should be made with caution in AA pts. Awareness of this among other specialists and primary care physicians may reduce the need for performing unnecessary TABs.

TABLE 1