A Rare Case of Four-year Complete Metabolic Response in Multisystem Anti–Jo-1 Antisynthetase Syndrome Assessed by 18F-FDG PET/CT

Antisynthetase syndrome (ASyS) is a rare idiopathic inflammatory myopathy with systemic manifestations, defined by the presence of anti-tRNA synthetase antibodies. Interstitial lung disease, particularly pulmonary fibrosis, is associated with a poorer prognosis. Here, we report a case of anti-Jo-1 positive antisynthetase syndrome assessed by 18F-FDG PET/CT, demonstrating muscular, articular, cutaneous, and pulmonary involvement, with a favorable outcome and complete resolution of abnormalities at 4-year follow-up, without evidence of associated malignancy. This case highlights the potential value of 18F-FDG PET/CT in the initial assessment and treatment monitoring of ASyS, offering a comprehensive approach to exclude underlying neoplastic disease and assess therapeutic response.