AB0671 First documentation of rs3pe affecting the hands on 18f-fdg whole body pet/ct in polymyalgia rheumatica

Background Remitting seronegative symmetrical synovitis with pitting oedema (RS3PE) syndrome describes a clinical entity characterised by distal synovitis with pitting oedema, the absence of rheumatoid factor (RhF) and an excellent response to glucocorticoid therapy.[1 Most frequently associated with polymyalgia rheumatica (PMR), tenosynovial sheath inflammation represents the magnetic resonance imaging (MRI) hallmark of this condition, with concomitant joint synovitis also present in some cases.[1 More recently, diffusely increased 18F-fluorodeoxyglucose (18F-FDG) uptake in the soft tissues around the ankles and feet has been described as the correlate of RS3PE on whole body positron emission tomography/computed tomography (PET/CT).[2 Objectives To document the clinical and radiologic appearance of RS3PE syndrome affecting the hands on MRI and whole body PET/CT in PMR patients. Methods Patients with newly diagnosed PMR were prospectively recruited as part of the Melbourne Predictors of Relapse in PMR (MPR-PMR) study. A standard physical examination was carried out with specific focus upon the presence of peripheral synovitis and pitting oedema. In patients with findings suggestive of RS3PE, clinical photography was undertaken. All study participants underwent a whole body PET/CT scan including dedicated views of the hands using the Phillips T/F machine prior to prednisolone commencement. To precisely identify anatomic correlates of abnormal 18F-FDG uptake in patients with RS3PE, MRI of the wrist and hand was performed using a 1.5 Tesla magnet. Results 3/35 patients (0.86%) were noted to have distal synovitis and pitting oedema of the hands at enrolment. Mean age was 70.9±10.1 years, two patients were male, and all were Caucasian. RhF and anti-citrullinated peptide autoantibodies were negative in all cases. On whole body PET/CT, intense 18F-FDG uptake was visualised at the wrist joint and hand in a distinctive volar distribution. MRI of the wrist and hand in two participants (contraindicated in the third) confirmed flexor tenosynovitis (white arrows) and intercarpal synovitis (yellow arrow) in keeping with RS3PE syndrome. Conclusions On whole body PET/CT, RS3PE syndrome is associated with a distinctive volar pattern of abnormal 18F-FDG uptake at the wrist and hand, which correlates with flexor tenosynovitis and intercarpal synovitis as previously described on MRI. References [1] Cantini F, Salvarani C, Olivieri I, et al. Remitting seronegative symmetrical synovitis with pitting oedema (RS3PE) syndrome: a prospective follow up and magnetic resonance imaging study. Annals of the Rheumatic Diseases. 1999;58(4):230–6. [2] Wang J, Pu C, Wang Z, Yang J. Remitting Seronegative Symmetrical Synovitis With Pitting Edema: Appearance on FDG PET/CT. Clin Nucl Med. 2017;42(6):492–5. Disclosure of Interest None declared