Significance of inflammation restricted to adventitial/periadventitial tissue on temporal artery biopsy

Objective: To evaluate the characteristics and significance of inflammation restricted (RI) to the adventitial and/or periadventitial tissue on temporal artery biopsy (TAB). Methods: We studied a retrospective cohort of 80 patients with RI, extending our earlier series of 39 patients. For comparison purposes, we collected the same data from 254 patients with transmural inflammation (TMI) and 81 TAB-negative patients. A review of the literature was also performed. Results: A final diagnosis of giant cells arteritis (GCA) and/or polymyalgia rheumatica (PMR) was observed in 86% of patients with RI. Compared to TMI, GCA diagnosis was significantly less frequently observed in patients with RI and in those TAB-negative (p < 0.0001), while cranial manifestations were significantly less frequent (p = 0.001) and ESR and CRP values at diagnosis significantly reduced (p < 0.0001). PMR, permanent visual loss, and large vessel involvement at diagnosis were equally present in the 3 subgroups. The median duration of prednisone therapy, the cumulative prednisone dosages, and the relapse and long-term remission rates were similar between patients with GCA-RI and those with TMI. The positive likelihood ratios (LRs) of pathological evidence of RI at TAB for GCA or GCA/PMR diagnoses were 0.88 (CI, 0.61–1.27) and 1.15 (CI, 0.67–1.99), while that of inflammation limited to adventitia was 1.37 (CI, 0.59–3.19) and 3.77 (CI, 0.53–26.72). In the literature review, the positive LR of RI for GCA diagnosis was 0.92 (CI, 0.68–1.25). Conclusion: A large part of the patients with RI have GCA/PMR, however, the diagnostic value of RI for GCA diagnosis is not relevant.