Histopathology reporting of temporal artery biopsy specimens for giant cell arteritis: results of a modified Delphi study

Abstract

The temporal artery biopsy (TAB) is regarded as the gold-standard test in the diagnosis of giant cell arteritis (GCA). There is a lack of agreement among experienced pathologists regarding the diagnostic features and classification of inflammation observed in TAB sections in the diagnosis of GCA.AimsThe aim of this research study was to establish consensus on the key parameters which should be included in a standardised reporting proforma for TAB specimens. We specifically investigated factors pertaining to clinical information, specimen handling and microscopic pathological features.MethodsA modified Delphi process, comprising three survey rounds and three virtual consensus group meetings, was undertaken by 13 UK-based pathology or ophthalmology consultants, with a 100% response rate across the three rounds. Initial statements were formulated after a literature review and participants were asked to rate their agreement using a nine-point Likert scale. Consensus was defined a priori as an agreement of ≥70% and individual feedback was provided after each round, together with data on the distribution of group responses.ResultsOverall, 67 statements reached consensus and 17 statements did not. The participants agreed on the core microscopic features to be included in a pathology report and felt that a proforma would facilitate consistent reporting practices.ConclusionsOur work revealed uncertainty surrounding the correlation between clinical parameters (eg, laboratory markers of inflammation and steroid therapy duration) and microscopic findings, and we propose areas for future research.

The spectrum of giant cell arteritis through a rheumatology lens

“…Temporal artery biopsy confirms a pathological diagnosis of GCA; since GCA was originally defined as a pathological construct, a positive biopsy by definition has high face validity as a method for confirming GCA [34]. Pathologists now consider various histological features as consistent with active arteritis [35]. "Healed arteritis" as described by the autopsy studies of Gilmour [3] and Ostberg [7] can sometimes be identified in patients with chronic long-standing disease [36], but the inflammatory infiltrate may persist even after one year of glucocorticoid treatment for GCA [37].…”