CD3 immunohistochemistry is helpful in the diagnosis of giant cell arteritis.

Objective: To evaluate whether CD3 staining performed routinely on temporal artery biopsy specimens might improve the sensitivity of temporal artery biopsy in patients with biopsy-negative GCA.

Methods: Two hundred and seventy biopsies were considered for this study, stained with haematoxylin and eosin and with an anti-CD3 antibody.

Results: The addition of CD3 staining modified the sensibility and the specificity of the histologic examination in 89.47 and 95.00%, respectively, with a positive and negative predictive values of 97.00 and 79.78% .

Conclusion: The addition of CD3 immunostaining to the classic histologic evaluation is accompanied by a significant increase in the sensibility with a comparable specificity.