Objective: To assess the prevalence and clinical significance of small-vessel vasculitis (SVV) surrounding an uninflamed temporal artery (TA) in patients diagnosed as having giant cell (temporal) arteritis (GCA) and/or polymyalgia rheumatica (PMR).
Methods: Patients with GCA and/or PMR (n = 490) were included in this multicenter prospective study. Slides of TA biopsy specimens were reviewed by 2 pathologists who were blinded with regard to clinical information. SVV was defined as aggregates of mononuclear inflammatory cells surrounding a capillary, distant from an uninflamed temporal artery. Clinical and biologic data of patients in the SVV group (n = 35) were compared with data of patients with biopsy-proven GCA (n = 280) and with negative TA biopsy findings (n = 175).
Results: SVV was diagnosed in 18 women and 17 men (mean +/- SD age 74.5 +/- 9.4 years). The group of patients with SVV had a higher proportion of men than in the entire GCA series, had systemic symptoms, headache, jaw claudication, and an abnormal temporal artery less frequently at clinical examination, but had symptoms of PMR more often than patients in the biopsy-proven GCA group (P = 2.6 x 10(-7), odds ratio 9.17 [95% confidence interval 3.44-24.4]). Levels of inflammation markers were significantly lower in the SVV group. Patients in the SVV group had fever less frequently than patients in the group with negative TA biopsy findings, but otherwise shared the same clinical (including PMR symptoms) and biologic features. Eighteen of the 94 patients with pure PMR (19%) had SVV.
Conclusion: SVV is often neglected by pathologists, and appears to be strongly associated with PMR symptoms in patients with a clinical diagnosis of GCA and/or PMR. However, SVV as a new diagnostic criterion for PMR must be assessed in prospective studies.