Multiple extra-articular synovial cysts accompanied by rheumatoid arthritis in the bilateral elbow joints: A case report

RATIONALE: Synovial cysts are well known in rheumatoid arthritis (RA), and most common in the popliteal fossa. They may produce lots of local symptoms and complaints, which may present initially as an unrelated clinical condition. Few studies have reported multiple extra-articular synovial cysts (MESCs) in the RA patients. Early diagnosis is crucial for patient treatment. PATIENT CONCERNS: A 50-year-old man without any special clinical histories found a soya bean size bump at the left elbow medially, then multiple lumps were found at bilateral elbows and gradually increasing. No pain, no activity, no redness, and swelling. Magnetic resonance imaging (MRI) showed multiple cystic lesions in the bursa and surrounding soft tissue of bilateral elbow joints. In addition, the elbow joint bursa was swollen and the synovial membrane was significantly thickened. DIAGNOSES: The man was diagnosed as RA with multiple extra-articular synovial cysts formation. INTERVENTIONS: The patient was performed tylectomy of the right elbow. Other lumps were punctured and injected with compound betamethasone injection. OUTCOMES: The bumps were reduced in size and the swelling relieved, and the patient was sent to the department of rheumatology and immunology for further treatment. LESSONS: In this case, it is difficult for the diagnosis of RA because of no relative histories and simultaneously multiple cystic lesions in multiple joints. Imaging examinations can show the characteristics of such kind of disease and be very helpful for the diagnosis and differentiate diagnosis.