Rice Body Formation Within a Peri-Articular Shoulder Mass

Most commonly associated with chronic inflammatory conditions, rice bodies represent an uncommon, nonspecific, often intra-articular inflammatory process. Presumably, rice bodies represent the sequelae of microvascular infarcts of the joint synovium. However, rice bodies have been seen in pleural fluid, in the setting of bursitis, and within the tendon sheath. The etiology and prognostic significance of rice bodies are not clear. MRI is the diagnostic imaging modality of choice for the evaluation of rice body formation. Here we present a case of a 28-year-old female with a history of rheumatoid arthritis (RA) who presented to her primary care physician with a palpable mass around her right shoulder which was presumed to be a lipoma. An initial ultrasound showed a fluid filled structure with internal debris. Subsequent MRI evaluation was confirmatory for subacromial-subdeltoid bursitis with rice body formation. The salient point of this report is to highlight the importance of patient-specific differential diagnosis. While lipomas are a very common benign soft tissue tumor, patients with RA often have disease-specific sequelae that should be included in the diagnostic deliberation. Thus, when ordering diagnostic testing for patients with a palpable mass and rheumatoid arthritis, MRI--possibly preceded by conventional radiography--is the most appropriate diagnostic algorithm.