Case Report: Unusual and Rare Presentation of Rheumatoid Arthritis as Multiple Large Synovial Cysts in Uncommon Locations.

Rheumatoid arthritis (RA) is a chronic autoimmune disorder primarily characterized by persistent synovitis, leading to joint destruction, deformities, and systemic involvement. Synovial cysts are rare extra-articular manifestations of RA, usually arising from inflamed synovial tissues. While most synovial cysts occur in typical locations like the knees and wrists, we present a unique case of RA manifesting as multiple large synovial cysts in uncommon locations. A 67-year-old female patient with a history of well-controlled RA presented with complaints of progressive swelling and discomfort in her upper arms and thighs, unresponsive to conventional RA management. Physical examination revealed large, fluctuant masses, which were non-tender but limited the range of motion in the affected limbs. Diagnostic imaging, including ultrasound and magnetic resonance imaging (MRI), confirmed the presence of multiple synovial cysts, each measuring over 5 cm in diameter, situated in atypical areas around the elbow, hip, and shoulder joints. Given the patient's history, these findings were initially unexpected, prompting further investigation to exclude differential diagnoses, such as lipomas, abscesses, and malignancies. Aspiration of the cysts revealed a synovial fluid consistent with RA pathology, confirming the diagnosis. This case highlights an unusual and rare presentation of RA. While synovial cysts are a known manifestation, their appearance in less typical locations emphasizes the importance of a comprehensive diagnostic approach. This case underscores the need for clinicians to consider atypical presentations when evaluating RA patients, particularly those with unusual swelling or masses that do not respond to standard treatments. Proper imaging and aspiration can facilitate accurate diagnosis, ensuring timely and appropriate management. Further research is needed to understand the mechanisms driving such atypical cyst formations and to optimize treatment strategies for similar cases.