Background/Purpose: Recent studies have suggested that giant cell arteritis (GCA) may be triggered by reactivation of varicella zoster virus (VZV) based on high rates of VZV antigen detected in temporal artery specimens. We attempted to replicate these findings and further validate the possible link between VZV and GCA by assessing clinical and serological markers of acute infection.

Methods: 24 patients suspected of having GCA were recruited prior to temporal artery biopsy (TAB) between July 2016 and April 2017. Patients were clinically evaluated for active and past VZV infection and had serum tested for VZV IgM and IgG. All were treated with high dose corticosteroids for at least one week while awaiting TAB and were followed clinically for at least one month. Formalin fixed biopsies were cut into a minimum of four sections and were stained using a mouse derived antibody against VZV antigen and reported by two experienced, blinded immunohistochemistry researchers.

Results: Mean age was 68 and 17 (71%) were female. 23 (96%) reported headache, 15 (63%) scalp tenderness and nine (38%) visual disturbance. Inflammatory changes were seen on seven (29%) biopsies; four had mural inflammation and three had limited periadventitial small vessel vasculitis (SVV). 16 (67%) met ACR criteria for GCA and 11 (46%) were assessed by the treating clinician as having definite or probable (>= 50% chance) GCA at two-week follow-up. No patients had clinical features of herpes zoster (shingles) at the time of enrolment. Six (25%) reported a history of zoster, 22 (92%) chickenpox and none had received the adult zoster vaccine. A single patient developed zoster ophthalmicus one week after commencing corticosteroids with subsequent ipsilateral biopsy showing SVV. All 24 biopsies stained negative for VZV antigen by immunohistochemistry. Of the 23 who had VZV serology, all were IgM negative. 21/23 (91%) were VZV IgG positive consistent with past exposure.

Conclusion: VZV antigen was not detected in biopsy specimens. IgM serology was negative in all 23 tested patients. Only one patient developed herpes zoster on follow-up. These interim results do not support a link between VZV and GCA.