Incidence of discordant temporal artery biopsy in the diagnosis of giant cell arteritis

Objective: We investigated the rate of discordant biopsy results (i.e., 1 side negative, 1 side positive) in patients who underwent initial bilateral temporal artery biopsies for suspected giant cell arteritis (GCA). Design: A cohort study. Participants: Consecutive patients undergoing temporal artery biopsy were enrolled. Of the 259 patients enrolled, 250 underwent initial bilateral temporal artery biopsies. Methods: Positive biopsies were defined based on accepted histologic definitions. Healed arteritis was considered a positive result. Clinical information was collected for all patients using a questionnaire administered by an ophthalmologist. Pathology results, including biopsy length (as measured by the pathologist), and laboratory information (i.e., serum erythrocyte sedimentation rate [ESR] and C-reactive protein [CRP] levels) were collected from digital patient records for statistical analysis. The main outcome was the rate of discordant biopsy in consecutive patients who underwent initial bilateral temporal artery biopsy. Results: Giant cell arteritis was confirmed in 62 (24.2%) of the 250 patients, including 3 patients with biopsies recorded as healed arteritis. The rate of discordant biopsy was 4.4% with 11 unilaterally positive biopsies. There was no statistical difference between the length of the left- and right-sided biopsies in either the unilaterally or bilaterally positive groups (p = 0.13 and p = 0.79, respectively). The average maximum ESR value for the bilateral group (58.7 mm/h) was significantly higher than the average maximum ESR value for the unilateral group (30.7 mm/h, p = 0.03). The average maximum CRP value for the bilateral group was 59.2 mg/L and 28.6 mg/L for the unilateral group (p = 0.30). Discordance between the localization of symptoms and the side of positive biopsy occurred in 3 patients (i.e., 3 patients had left-sided symptoms only, yet a right-sided positive biopsy). Conclusions: The rate of discordant biopsies in patients who underwent initial bilateral temporal artery biopsies was considerable in our patient cohort. Given this reasonably high rate of discordance between sides, as well as the lack of correlation between side of positivity and laterality of presenting symptoms, we recommend initial bilateral temporal artery biopsies to enhance the diagnostic certainty of the disease.