Clonal Hematopoiesis in Giant Cell Arteritis

Inclusion Criteria: * Patients with suspected active GCA entering into a fast-track work-up and healthy matched controls. * Capability of providing valid consent to study enrollment. * Possibility of performing temporal artery biopsy within three hours from enrollment. Exclusion Criteria: * Active concurrent viral, fungal or bacterial infections (including active/latent tuberculosis treated for less than 4 weeks, HIV and Hepatitis B/C virus (HBV/HCV) infections. * Concurrent systemic inflammation not attributable to GCA (inflammatory diseases in treatment-free remission are accepted). * Use of other immunosuppressive agents in the last 3 months. * Use of systemic steroids (any dose in the last week, \> 15 mg/die of prednisone equivalent in the last month). * Solid or hematologic malignancies (active or with less than 6 months free of disease or antiblastic chemotherapy (hormone therapy is allowed). * Previous solid or hematopoietic stem cell transplantation (corneal transplants are allowed). * Any systemic immunosuppressive or steroidal therapy. * Chronic renal failure with Glomerular Filtration Rate (GFR) \< 45 ml/min \*1.73 m2. * Moderate-severe liver failure (Child-Pugh B or C), hepatitis in stages of activity. * Diabetes mellitus. * Heart failure with New York Heart Association score (NYHA) \>=2. * Severe hypoproteinemia/malnutrition. * Chronic respiratory failure requiring O2 therapy or ventilation therapy at home. * Any other condition judged by the local investigato…