Rheumatoid Arthritis-Associated Shoulder Rice Body Bursitis: Arthroscopic Management and Mechanistic Implications.

BACKGROUND Rice body bursitis is a rare synovial lesion with an incompletely understood pathogenesis. It typically manifests as painless joint swelling and may involve bursae around joints throughout the body. Due to the lack of specific symptoms, this condition is frequently misdiagnosed or overlooked, resulting in delayed treatment. This report describes a case of rice body bursitis of the shoulder joint secondary to rheumatoid arthritis. CASE REPORT A 55-year-old woman with a history of rheumatoid arthritis presented with 1 month of right shoulder swelling, pain, and restricted motion. Physical examination revealed shoulder flexion limited to 95° and abduction limited to 50°. Magnetic resonance imaging demonstrated multiple hypointense loose bodies in the subacromial-subdeltoid bursa. Arthroscopic debridement was performed, during which more than 100 white rice bodies (0.4-1.1 cm in diameter) were identified. Postoperative histopathological analysis confirmed bursitis with rice body formation. At the 6-month follow-up, the patient's Constant-Murley score improved from 42 to 86. CONCLUSIONS Arthroscopic debridement effectively restored shoulder function in rheumatoid arthritis-associated subacromial rice body bursitis. The intraoperative observation of capillary networks surrounding some rice body clusters, without vascular penetration into individual rice bodies, supports the synovial shedding hypothesis. Early magnetic resonance imaging or ultrasound screening is essential to identify atypical isolated shoulder involvement.