Objective. To investigate the incidence and clinical and histopathologic features of giant cell (temporal) arteritis (GCA) in the Caucasian population of Iceland.

Methods. AH patients diagnosed between 1984 and 1990 were included. Case ascertainment for the study was done in 2 ways: 1) a computerized search from all hospitals and primary care clinics for the diagnosis of GCA, and 2) a review of all temporal artery biopsies performed during the 7-year period.

Results. One hundred thirty-three patients with GCA were identified. All fulfilled the 1990 American College of Rheumatology criteria for the classification of GCA. The incidence rate for the population 50 years and older was 27/100,000 (36/100,000 and 18/100,000 for women and men, respectively). Clinical findings included the following: mean age at diagnosis 72.5 years for women and 70.3 years for men, new headache 63.2%, abnormal temporal artery on palpation 43.6%, mean erythrocyte sedimentation rate 88 mm/hour, symptoms of polymyalgia rheumatica 48.1%, and visual disturbances 14.3%. A total of 744 patients underwent temporal artery biopsy during the 7-year period; 16.8% had a positive biopsy result. All 133 patients with the diagnosis of GCA underwent a temporal artery biopsy; 94% had a positive result. Histopathologic findings from the positive biopsies included a fragmented internal elastic lamina in 99.2%, giant cells in 65.6%, and fibrinoid necrosis in 12%.

Conclusion. Compared with previous epidemiologic surveys, this study shows a high incidence of biopsy-proven GCA in Iceland.