"Rice Body"-Like Synovial Particles on Magnetic Resonance Imaging: What Is the Spectrum of Diagnoses?

Area of Science:

• Orthopedic imaging
• Rheumatology diagnostics
• Pathology of synovial joints

Background:

• "Rice bodies" are fibrinous loose bodies arising from hyperplastic synovial villi.
• Historically linked to tuberculosis and inflammatory arthritis.
• Lack of studies correlating MRI findings with histology and diagnoses.

Purpose of the Study:

• To correlate magnetic resonance imaging (MRI) appearances of rice body-like particles with histological findings.
• To identify and describe the spectrum of underlying diagnoses associated with these MRI findings.

Main Methods:

• Retrospective cross-sectional study of 100 patients with "rice bodies" noted in MRI reports (June 1992-July 2022).
• Inclusion criteria: confirmed MRI finding of rice bodies, available images, and established diagnosis via follow-up or histology.
• Exclusion criteria: unavailable MRI or insufficient follow-up for diagnosis.

Main Results:

• 52 patients met inclusion criteria; 37% had prior surgery (73% arthroplasty).
• Associated diagnoses: inflammatory arthritis (52%), infection (25%), synovial chondromatosis (8%), osteoarthritis (6%), bursitis (6%), and adverse local tissue reaction (4%).
• In arthroplasty cases, rice bodies were linked to infection (71%) and adverse local tissue reaction (14%).

Conclusions:

• MRI findings of rice body-like particles are not specific to tuberculosis or inflammatory arthritis.
• Consider non-mycobacterial infections, particularly in patients with arthroplasty.
• Broadens the differential diagnosis for rice body-like findings on MRI.