Background: Giant cell arteritis (GCA) is the most common form of primary systemic vasculitis in patients aged >50 years. It predominantly affects the cranial arteries; however, extra-cranial disease involving the aorta and its major branches, known as large-vessel GCA (LV-GCA), can be present in 20-80% of cases, depending upon the imaging modality used for screening the disease. We aim to compare the clinical features and outcomes of GCA patients with exclusive cranial, exclusive LV and combined cranial and LV involvement. Methods: Single centre observational retrospective study, using data from patients diagnosed with GCA registered at the Rheumatic Diseases Portuguese Registry (Reuma.pt). All patients underwent ultrasound of both temporal (TA) and axillary (AX) arteries ± facial (FA), occipital (OC), subclavian (SC) or common carotid (CC) arteries at the time of diagnosis. Only patients with the presence of “halo sign” in at least one of these arterial segments were included. Three groups of patients were established according to their ultrasound results: i) exclusive cranial-GCA in cases of TA, FA, or OC involvement; ii) exclusive LV-GCA in cases of AX, SC, or CC involvement; and iii) cranial- and LV-GCA in cases of both cranial and LV involvement. Univariate analysis was performed using T-test, Chi-square and ANOVA, as appropriate. Multivariate analysis was performed using logistic regression modelling. Results: We included 81 patients with GCA, 55 (67.9%) females, with a mean ± SD age of 75.8 ± 8.6 years. Halo sign was found on the TAs of 66/81 (81.5%) patients, AXs of 38/81 (46.9%) patients, FAs of 37/71 (52.1%) patients, OCs of 15/58 (25.9%) patients, SCs of 27/46 (58.7%) patients and CCs of 12/57 (21.1%) patients. A total of 37 (45.7%) cases had exclusive cranial-GCA, 44 (54.3%) had cranial- and LV-GCA and 14 (17.3%) had exclusive LV-GCA. Table 1 summarises the differences between the three groups. Regarding clinical manifestations, exclusive cranial-GCA was more commonly associated with temporal headache, as opposed to exclusive LV-GCA, in which patients were less likely to experience temporal or frontal headache, as well as jaw claudication, scalp tenderness or a cranial ischemic event. Concerning physical examination, exclusive LV-GCA was associated with abnormalities of the upper limb arteries and lack of TA changes. No significant differences were found between groups regarding demographics, comorbidities, relapses or mortality. Multivariate analysis, adjusted for jaw claudication, scalp tenderness, frontal and temporal headache, cranial ischemic events, abnormalities of the TA and upper limb arteries on examination, was performed to assess the association between these variables and the three GCA groups. Occurrence of a cranial ischemic event was independently associated with a lower probability of exclusive LV-GCA [OR: 0.069 95%CI: 0.009-0.526, p=0.010]. No other independent predictors were found. Conclusions: GCA can encompass various patterns of vascular disease on ultrasound. LV involvement was frequently found in these patients, including in cases without evidence of cranial disease, highlighting the need to incorporate LV assessment in the diagnosis of GCA. Patients in the group of exclusive LV-GCA had fewer cranial manifestations and more abnormalities on upper limb arteries on examination than the other groups. Presence of a cranial ischemic event was an independent negative predictor for exclusive LV-GCA. No differences were found between groups regarding the clinical outcomes at two years. Further studies with longer time of follow-up are needed. Disclosures: None