Intraosseous Ganglion Cyst of the Sternoclavicular Joint.

We report the case of a 63-year-old man who presented with a mass on the right clavicle near the sternoclavicular joint. He had received prior puncturing treatment, but relapsed each time. Magnetic resonance imaging revealed that the mass was a ganglion cyst, which appeared to be connected to the right clavicle. Excisional biopsy revealed that the cyst was an intraosseous ganglion cyst, and the cavity was connected to the sternoclavicular joint. The cavity was filled with an artificial bone graft after curettage to prevent fracture. Histological examination showed that the cyst wall had no lining cells and consisted of fibrous connective tissue. To the best our knowledge, this case is the first report of an intraosseous ganglion cyst of the sternoclavicular joint.