BACKGROUND : Age at onset of large-vessel vasculitis (LVV) is commonly used to distinguish giant cell arteritis (GCA) and Takayasu arteritis (TA). However, LVV between age 50 and 60 years may be difficult to classify. METHODS : We conducted a retrospective study including LVV aged between 50 and 60 years at onset (LVV50-60, cases) and compared them to LVV aged over 60 years (LVV>60, controls). LVV was defined histologically and/or morphologically. Controls fulfilled ACR 1990 criteria for GCA or presented isolated aortitis. RESULTS : We included 183 LVV50-60 and 183 gender-matched LVV>60. LVV50-60 had more frequent peripheral limb manifestations (23 vs. 5%), and less frequent cephalic (73 vs. 90%) and ocular signs (17 vs. 27%) than LVV>60. Compared to LVV>60, CT angiography and PET/CT scan were more frequently abnormal in LVV50-60 (74 vs. 38%, and 90 vs. 72%, respectively), with aorta being more frequently involved (78 vs. 47%). By multivariate analysis, absence of cephalic symptoms, presence of peripheral limb ischemia and aorta involvement, and increased CRP level were significantly associated with LVV50-60 presentation compared to LVV>60. At last follow-up, compared to LVV>60, LVV50-60 received significantly more lines of treatment (2 vs. 1), more frequent biologics (12 vs. 3%), had more surgery (10 vs. 0%), and had higher prednisone dose (8.8 vs. 6.5 mg/d) at last follow-up, CONCLUSION: LVV onset between 50 and 60 years identifies a subset of patients with more frequent aorta and peripheral vascular involvement and more refractory disease compared to patients with LVV onset after 60.