Synovial osteochondromatosis of the sternoclavicular joint in early adolescence.

Synovial osteochondromatosis is a rare benign disorder characterised by cartilaginous metaplasia of the synovium, most often affecting large joints. We describe an unusual case in the sternoclavicular joint of an adolescent, who presented with a localised swelling. Imaging demonstrated multiple calcified loose bodies, and the diagnosis was confirmed histologically following surgical excision. Management consisted of removal of the loose bodies with consideration of synovectomy to reduce recurrence. Early recognition is crucial to prevent progressive joint damage.