Correlations between histopathological findings and clinical manifestations in biopsy-proven giant cell arteritis

Objective: To correlate histopathological features of positive temporal artery biopsy (TAB) and clinical manifestations of the disease in a large single-center population-based cohort of patients with biopsy-proven giant cell arteritis (GCA). Methods: A pathologist with expertise in vasculitis and blinded to clinical data and final diagnosis reviewed all TABs performed for suspected GCA at our hospital between January 1986 and December 2013. Histopathologic features evaluated were: the severity of inflammation and intimal hyperplasia, both graded on a semiquantitative scale (mild = 1, moderate = 2, severe = 3), the presence of intraluminal acute thrombosis, calcifications, giant cells, fibrinoid necrosis and laminar necrosis. Results: 274 patients had a final diagnosis of biopsy-proven GCA and were included in the study. Cranial ischemic events (CIEs) were observed in 161 (58.8%), visual manifestations in 79 (28.8%) and permanent (partial or complete) visual loss in 51 (18.6%) patients. Predictors for the development of CIEs were older age (OR = 1.057, 95% CI 1.019-1.097, p = 0.003), lower ESR values (OR = 0.990, 95% CI 0.981-0.999, p = 0.026) as well as the presence of giant cells (OR = 1.848, 95% CI 1.045-3.269, p = 0.035) and laminar necrosis at TAB (OR = 2.334, 95% CI 1.187-4.587, p = 0.014). Predictors for the development of permanent visual loss were lower CRP values (OR = 0.906, 95% CI 0.827-0.992, p = 0.033) and the presence of calcifications at TAB (OR = 3.672, 95% CI 1.479-9.121, p = 0.005). Fibrinoid necrosis was not observed in any of the TABs evaluated. Conclusion: Pathological features of TAB may predict some manifestations of GCA. These findings may have implications for patients' management.