Pilot Study to evaluateThrombomodulin to Rule Out Giant Cell Arteritis (GCA) in Polymyalgia Rheumatica (PMR) Patients. (THROPIQ)

Inclusion criteria

• Patient who has given oral consent
• Patient > 50 years of age

Patients with PPR, meeting ACR/EULAR 2012 criteria:

• age > 50 years at onset of symptoms
• inflammatory limb-girdle pain
• elevated ESR (>20 mm/hr) and/or CRP (> 10 mg/l)
• AND Score ≥ 4 points among

• Morning stiffness > 45 minutes (2 pts)
• Hip pain or limitation of amplitude (1 pt)
• Rheumatoid factor or anti-CCP antibodies negative (2 pts)
• Absence of other joint pain (1 pt)

Exclusion criteria

• Patient not affiliated to national health insurance
• Patient under legal protection (curatorship, guardianship)
• Patient subject to a measure of legal safeguard
• Pregnant or breast-feeding women
• Adult patient unable to provide consent
• Patient having received corticosteroid or immunosuppressive treatment in the month prior to inclusion
• Patient with a contraindication to corticosteroid therapy
• Patients with an active infection, neoplasia or other inflammatory/autoimmune condition
• Patients with late onset rheumatoid arthritis.
• Conditions rendering vascular imaging unfeasible or uninterpretable:
• For angio-CT: allergy to iodine, renal failure (CKD <30 mL/min)
• For PET scan: unbalanced diabetes NB: only one of the two vascular imaging techniques will be performed, depending on the patient&#39;s condition and the technical resources available.

Secondary exclusion criteria:

• Final diagnosis of paraneoplastic PMR
• Final diagnosis of RA
• Negative PET scan (if performed 72 hours after glucocorticoid introduction)