VZV, temporal arteritis, and clinical practice: False positive immunohistochemical detection due to antibody cross-reactivity.

Varicella Zoster Virus (VZV) antigen has been reported to be present in the majority of temporal artery biopsies with implications for antiviral treatment in patients with giant cell arteritis. Using immunohistochemistry with VZV antibodies we found reactivity present in diverse myocyte types (smooth, skeletal and cardiac), diverse arteries (including temporal, coronary, and vertebral) and diverse clinical settings. This phenomenon is likely due to shared epitopes between VZV proteins and muscle elements and not due to actual VZV infection. We conclude that VZV immunohistochemistry should be used with caution for screening of VZV infection in the setting of temporal artery biopsies.