A Case of Idiopathic Massive Rice Bodies in the Knee Joint without Rheumatoid Arthritis or Tuberculosis and a Literature Review

Rice bodies are materials with an amorphous nucleus and a fibrin layer found floating in the synovial space and bursa. These bodies have often been detected in patients with rheumatoid arthritis, tuberculous arthritis, and bursitis. Although the etiology and pathogenesis of rice bodies are not yet fully understood, it has been hypothesized that they might be caused by chronic inflammation originating from the synovium. However, we report on a case of idiopathic massive rice bodies in the knee joint without evidence of inflammatory articular disease or infection including rheumatoid arthritis, seronegative spondyloarthritides, tuberculosis, or bacterial or fungal infection. (J Rheum Dis 2016;23:316-320)