Extra-articular Synovial Chondromatosis of the Subacromial-Subdeltoid Bursa Mimicking Rice Body Synovitis: A Case Report.

Synovial chondromatosis can lead to proliferation of the synovium followed by the appearance of multiple cartilaginous nodules, most commonly in large joints. Extra-articular involvement of the subacromial-subdeltoid bursa could resemble an inflammatory or infectious process, especially if the chondromatosis is present in the form of rice bodies. A 37-year-old right-hand-dominant male presented with left shoulder pain for three months, with restricted shoulder motion and pain during overhead activities, with no past medical history of trauma or surgery. He presented to the orthopedic outpatient department. Blood tests, including inflammatory markers, rheumatoid factor, and tuberculosis investigations, were normal. X-rays were unremarkable, but magnetic resonance imaging demonstrated enlargement of the bursa with multiple nodular loose bodies resembling rice bodies. Open excision revealed over 100 loose bodies measuring 3-10 mm. Synovectomy was performed, and histopathology demonstrated the presence of hyaline cartilage, confirming the diagnosis of synovial chondromatosis. The postoperative phase was uneventful. The patient underwent rehabilitation and demonstrated improved pain relief and shoulder function. At the six-month follow-up, he had improved shoulder range of motion and was free from pain, swelling, or clinical recurrence. This case highlights that extra-articular synovial chondromatosis can closely resemble rice body synovitis, making magnetic resonance imaging valuable for preoperative assessment, while histopathological examination remains essential for definitive diagnosis.