Clinical Images: Rice bodies in subacromial bursa at initial presentation of rheumatoid arthritis

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The patient, an 86‐year‐old White female, presented with polyarticular joint pain of 3 months’ duration. Examination revealed evidence of inflammatory arthritis, with a Clinical Disease Activity Index (CDAI) score of 61. Ultrasound of the right shoulder in anterior longitudinal and transverse views revealed an effusion in the subacromial bursa with several hypo‐ to hyperechoic round and oval structures in the subacromial bursa, most compatible with rice bodies (Figure 1). Synovial fluid aspirate revealed 9961 nucleated cells/mL, 52% lymphocytes, and negative crystal analysis. Laboratory workup showed elevated Erythrocyte sedimenation rate (49 mm/h), C‐reactive protein (18.8 mg/L), rheumatoid factor (1073 IU/mL), and anti‐cyclic‐citrullinated peptide (>250 Units). The patient was diagnosed with rheumatoid arthritis (RA) and started on prednisone 20 mg daily (tapered over the next 4 weeks), methotrexate 25 mg weekly, hydroxychloroquine 400 mg daily with improvement in CDAI score to 5.5 six months later.

Figure 1.

Gray mode sonography of the right shoulder in the (A) anterior longitudinal and (B) anterior transverse views showing multiple rice bodies as hypo‐ to hyperechoic round to oval structures (*) in the aubacromial bursa (SAB). B, Biceps tendon; H, Humerus; D, Deltoid.

Rice bodies are polymorphic free proteinaceous masses, appearing as 3‐ to 7‐mm ceramic white rice grains located in the articular cavity, periarticular bursae, or tendon sheaths (1). Pathogenesis involves synovitis, synovial proliferation and secondary degeneration, synovial tissue micro‐infarction after ischemia, and encapsulation by fibrin. Histopathology shows an amorphous acidophilic core surrounded by collagen and fibrous tissues, microvillous synovial hyperplasia, and inflammatory infiltrate. Rice bodies have mostly been reported in infectious arthropathies, especially tuberculosis. However, they can also be seen in other forms of inflammatory arthritis such as RA, where they can be present at the onset of the disease and do not correlate with disease activity (2). Ultrasound can be a useful diagnostic tool and shows mobile, hypoechoic to hyperechoic, well‐defined biconcave specks or grains in the synovial or bursal fluid (3). Occasionally, individual rice bodies can be difficult to delineate, giving the impression of a soft tissue mass, debris, or blood. Other mimics include tophi and calcium pyrophosphate deposits, differentiated by other sonographic features and synovial fluid analysis (4). Management includes treatment of underlying inflammatory/infectious pathology, elective removal by lavage and aspiration, urokinase and fibrinolysis promoting agents, and synovectomy.

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