Clinicopathologic correlations in giant cell arteritis: a retrospective study of 107 cases

To correlate the pathologic findings of temporal artery biopsies in patients clinically defined as positive, presumed, or negative for giant cell arteritis (GCA).

Retrospective case series.

Patients evaluated for GCA.

Temporal artery biopsies examined between 1989 and 2007 were studied. Clinical information and residual tissue for immunohistochemical staining was identified in 107 patients. Clinical information was used to make a diagnosis of "positive," "presumed," or "negative" GCA. The biopsies were reviewed in a masked fashion and classified as "positive," "indeterminate," or "negative" based on published, classic pathologic diagnosis (CPD) criteria. All biopsies were immunostained for CD3 and CD68 and graded as "negative," "mildly" (+), "moderately" (++), or "markedly" (+++) positive. Clinical and pathologic results were correlated and a modified pathologic diagnosis classification (MPD) scheme was developed. The modified scheme was compared in a masked fashion with the final clinical diagnosis and positive and negative predictive values (PVs) were calculated.

Pathologic diagnosis and final clinical diagnosis.

Using the MPD classification, there were 25%, 16%, and 61% positive, indeterminate, and negative biopsies, respectively. There was excellent correlation between the modified pathologic criteria and final clinical diagnosis (correlation coefficient 0.997; P<0.0001; kappa = 0.81). The positive PVs for CPD and MPD were 85% and 96%, respectively. The negative PVs for CPD and MPD were 64% and 61%, respectively. Positive and negative biopsies strongly correlated with clinical diagnoses of positive and negative for GCA, respectively, whereas indeterminate cases moderately correlated with presumed GCA. The diagnosis did not change from the original biopsy in 11 patients who had a second biopsy. Immunostaining for CD 68 was helpful in several indeterminate cases.

We recommend using the modified histologic classification of temporal artery biopsies. There are indeterminate cases that cannot be further defined using current pathologic classification criteria. A second biopsy has very limited value. Immunostaining for CD68 may be helpful in indeterminate cases, although the diagnosis in these cases is based on clinical judgment.