Yield of Frozen Section Versus Permanent Pathology in Temporal Artery Biopsy for Giant Cell Arteritis

There is significant debate as to whether bilateral temporal artery biopsies (TABs) are required for the diagnosis of giant cell arteritis (GCA). Discordance rates have varied in the literature and the utility of TAB frozen sections are unclear. We set out to evaluate the discordance rate of TABs and determine the sensitivity and specificity of TAB frozen versus permanent section pathology results for GCA.

Poster 237 Yield of Frozen Section versus Permanent Pathology in Temporal Artery Biopsy for Giant Cell Arteritis Devon Cohen1, John Chen1, Bryan Neth1, Nouran Sabbagh1, David Hodge1, Kenneth Warrington1, Jonathan Fillmore1, Muhammad Bhatti1 1 Mayo Clinic, Rochester, Minnesota, USA Introduction: There is significant debate as to whether bilateral temporal artery biopsies (TABs) are required for the diagnosis of giant cell arteritis (GCA). Discordance rates have varied in the literature and the utility of TAB frozen sections are unclear. We set out to evaluate the discordance rate of TABs and determine the sensitivity and specificity of TAB frozen versus permanent section pathology results for GCA. Methods: Retrospective chart review of 795 patients, > 40 years of age, who underwent TAB with both frozen and permanent sectioning performed at our institution from January 1, 2010 to December 1, 2018. Results: GCA was confirmed in 120 of 795 (15.1%) cases; 65% were female with a median age of 73 years. Frozen section was positive in 103 (85.8%) cases with 4 false positives (0.6%) and 21 false negatives (17.5%). There was a 5.5% discordance rate among bilateral TABs. However, among positive cases that underwent bilateral TABs, 40.8% were discordant between the two sides. Of the TAB positive cases, the median biopsy length was 2.475 cm, median sedimentation rate was 56 mm/hr, C-reactive protein 53.9 mg/L, and platelet count 341.5 K/µL. Variables correlated with a positive TAB were biopsy length, CRP, and jaw claudication. Conclusions: The overall discordance rates between sides was low, but was fairly high among positive TABs (40.8%), which suggests that it may be beneficial to do bilateral TABs in patients with a high pretest probability of GCA. TAB frozen sections have 82.5% sensitivity and 99.4% specificity for detecting vascular inflammation consistent with GCA. Based on these results, a negative frozen section result should not be relied upon to refute the diagnosis of GCA. However, if the frozen section is positive on the first TAB, a contralateral TAB is not required given the very low false positive rate. References: Boyev et al., Efficacy of unilateral versus bilateral temporal artery biopsies for the diagnosis of giant cell arteritis, Am J Ophthalmol, 128, 211-5, 1999. Breuer et al., Association between histological features in temporal artery biopsies and clinical features of patients with giant cell arteritis, Isr Med Assoc J, 15, 271- 4, 2013. Frohman et al., New developments in giant cell arteritis, Surv Ophthalmol, 61, 400-421, 2016. Keywords: Neuro-ophth & systemic disease (eg. MS, MG, thyroid), Vascular disorders Financial Disclosures: The authors had no disclosures. Grant Support: None. Contact Information: M. Tariq Bhatti- [e-mail]; 507-284-3726 388 | North American Neuro-Ophthalmology Society