Anti-OJ antibody-positive anti-synthetase syndrome with repeated arthritis, fever, and recurrent liver cancer: a case report.

Background: Anti-isoleucyl-transfer RNA synthetase (anti-OJ) autoantibody-positive anti-synthetase syndrome (ASS) is a rare systemic autoimmune disease that manifests as an inflammatory myopathy and interstitial lung disease. We present a case of an anti-OJ antibody-positive ASS, with recurrent joint pain and fever, significantly elevated inflammatory markers, occult myositis but no interstitial pneumonia. This clinical presentation of an anti-OJ antibody-positive ASS has not been reported before. Case Description: A 75-year-old male, was admitted to our hospital complaining of recurrent joint pain for more than 1 year, recurrent fever for 6 months, and recurrence of joint pain and fever for 1 week. The patient had a history of chronic viral hepatitis B, hepatocellular carcinoma (HCC) surgery 11 years ago, hypertension and type 2 diabetes. In the past year, the patient visited Departments of orthopedics, Infectious Medicine and rheumatology for many times, and has undergone positron emission tomography-computed tomography (PET-CT), bone marrow puncture and other examinations, but the cause was still unknown. On admission, physical examination showed that the temperature was 39.6 ℃, and there was tenderness in multiple joints and muscles, such as the left ankle, the right shoulder, the left wrist, biceps brachii and quadriceps femoris, and so on. The laboratory results showed white blood cell (WBC) count of 30,500/µL (neutrophils: 90.1%), C-reactive protein (CRP): 140.79 mg/dL, Creatine Kinase and creatine kinase-MB were normal. Because of the muscle tenderness, myositis antibody tests were performed and the anti-OJ autoantibody was positive. Asking the medical history in detail, the patient had myasthenia, which was covered up due to prominent joint pain and fever. The patient had no interstitial pneumonia and mechanic's hand. Recurrent hepatocellular carcinoma was confirmed 1 year after the diagnosis of ASS, and the clinical symptoms were relieved after surgical resection. Conclusions: We report this rare case of anti-OJ antibody-positive ASS with atypical manifestations to raise awareness of the disease for clinicians. For patients with recurrent unexplained arthritis with fever, we should consider ASS, and myositis antibody tests should be performed if necessary. Patients with a history of tumours should be monitored for tumour recurrence.