Small-vessel vasculitis surrounding an uninflamed temporal artery and isolated vasa vasorum vasculitis of the temporal artery: two subsets of giant cell arteritis.

OBJECTIVE: To evaluate the frequency and clinical characteristics of periadventitial small-vessel vasculitis (SVV) and isolated vasa vasorum vasculitis (VVV).
METHODS: We identified 455 temporal artery biopsies performed in residents of Reggio Emilia, Italy between 1986 and 2003. Slides of temporal artery biopsy specimens were reviewed by a pathologist who was blinded with regard to clinical data. SVV was defined as inflammation of the small vessels external to the temporal artery adventitia, and VVV was defined as isolated inflammation of temporal artery vasa vasorum. Medical records of patients with SVV and/or VVV were reviewed, and demographic, clinical, laboratory, and followup data were collected. For comparison purposes, we collected the same data from an equal number of randomly selected patients with evidence of classic giant cell arteritis (GCA).
RESULTS: Sixteen patients had SVV, 18 had isolated VVV, and 5 had both SVV and VVV. Compared with patients with classic GCA, the frequencies of headache, scalp tenderness, abnormalities of temporal arteries, jaw claudication, anorexia, and weight loss, the levels of acute-phase reactant at diagnosis, and the initial and cumulative doses prednisone were significantly lower and the frequency of peripheral synovitis was higher in the patients with SVV, and the frequency of cranial ischemic events was similar in the 2 groups. In contrast, the clinical characteristics and erythrocyte sedimentation rate at diagnosis of patients with isolated VVV were similar to those of patients with classic GCA.
CONCLUSION: Our findings indicate that isolated VVV and SVV should be considered part of the histopathologic spectrum of GCA.