AB0440 The fine line between takayasu and giant cell arteritis: a retrospective study

Background Takayasu arteritis (TAK) and Giant cell arteritis (GCA) are classified as two different vasculitides.[1] The differentiation is based on age at onset (under 40y for TAK, above 50y for GCA) and vascular distribution (aorta and its primary branches for TAK and mainly extracranial arteries for GCA). However, both diseases involve large vessels and share histopathology findings. Objectives Our goal is to describe a series of patients above the age of 50y with large vessel arteritis and vascular involvement typical of TAK. Methods Eighteen Patients (median age 64y, 16 females) were selected from 3 centers in Israel. A retrospective review of the cases was preformed with special emphasis on clinical characteristics (including clinical course and outcome), laboratory values and vascular involvement. Vascular imaging by CT angiography, MRI angiography or planar angiography was done in all cases. Results Five patients fulfilled the ACR criteria for GCA, 5 the ACR criteria for TAK, 3 both GCA and TAK criteria, while 5 patients had clear involvement of large vessels without fulfilling the criteria for either disease. The dominant presenting symptoms were constitutional, while only a few patients had cranial or peripheral symptoms. On physical examination, 61% had signs of vascular compromise including: blood pressure arm differences, non palpable limb pulses or vascular bruits. All patients had elevated acute phase reactants, 78% had anemia. Temporal artery biopsy showed giant cell arteritis in 6 out of 9 biopsies. The majority (78%) showed either involvement of the ascending aorta, the aortic arch, descending aorta or a combination of these. The distribution of vessel involvement was as following: carotid arteries in 9 patients, subclavian arteries in 12, axillary arteries in 5, abdominal aorta in 9, mesenteric or celiac trunk in 7, renal arteries in 3, iliac arteries in 7 and femoral arteries in 2. All the patients were treated with prednisone and 50% with steroid sparing drug. Nine out of 15 patients (60%) that have completed at least 1 year of follow-up achieved remission. Three additional patients had a partial remission. Three patients of the remission group relapsed. A comparison between the patients who fulfilled the ACR criteria for GCA and those who fulfilled for TAK showed that the first group was slightly older (70y vs. 64y) and had more constitutional symptoms while the second group had more peripheral symptoms and more vascular involvement signs in physical examination. The acute phase reactants were slightly higher in the GCA group. However, no substantial differences in the distribution of vascular involvement, type of treatment or outcome measures were observed. Conclusions Vascular involvement typical of TAK in patients above the age of 50y with large vessel arteritis seems to be more frequent than previously assumed. The differences between those who fulfill the criteria for each disease are minor. Our findings support the assumption that TAK and GCA represent a spectrum of the same disease. References Fries JF, Hunder GG, Bloch DA, et al. The ACR 1990 criteria for the classification of vasculitis. Arthritis Rheum. 1990;33:1135-6. Disclosure of Interest None Declared