The Adequate Number of Histopathology Cross-sections of Temporal Artery Biopsy in Establishing the Diagnosis of Giant Cell Arteritis

Purpose: to determine the appropriate number of histopathological cross-sections that are required for a conclusive diagnosis of giant cell arteritis (gca). methods: in this cross-sectional study, the number of sections per slide for paraffin-embedded blocks for 100 randomly selected cases where gca was suspected and those for negative temporal artery biopsies (tabs) were compared with the number of cross-sections per specimen for eight positive-tabs. all aforementioned examinations were conducted at our center from 2012 to 2016. then, negative-tabs were retrieved and re-evaluated using light microscopy consideringthe histopathological findings of gca. results: ninety-five paraffin blocks were retrieved. the original mean biopsy length was 15.39 ± 7.56 mm. comparison of the mean number of cross-sections per specimen for both the positiveand negative-tabs (9.25 ± 3.37 and 9.53 ± 2.46) showed that 9.87 ± 2.77 [95% confidence intervals (ci)] cross-sections per specimen were sufficient for a precise gca diagnosis. there was no statistically significant difference in the mean biopsy length (p = 0.142) among the eight positive-tabs. similarly, no significant difference was observed in the number of cross-sections per specimen (p = 0.990) for positive-tabs compared to those for the negative-tabs. after the retrieval of negative-tabs, the mean number of total pre- and post-retrieval cross-sections per specimen was 17.66 ± 4.43. among all retrieved specimens, only one case (0.01%) showed the histopathological features of healed arteritis. conclusion: positive-tabs did not reveal more histological cross-sections than the negative ones and increasing the number of cross-sections did not enhance the accuracy of tab.