Unusual finding after contrast injection of a solitary bone cyst. A case report.

Injection of radiopaque contrast into a solitary bone cyst (SBC) prior to methylprednisolone acetate (MPA) injection has been previously reported. We report an unusual finding during the injection of radiopaque contrast in the treatment of one case of SBC of the femur: a bicameral appearance of the cyst was observed; no filling of the proximal cavity occurred and immediate perfusion of the femoral vein with contrast was noted. In cases of SBC such as this one, percutaneous autologous marrow or corticosteroid injection may fail to be effective. Furthermore there exists the potential risk of fat embolus secondary to bone marrow injection. Based on these findings in the case reported, we suggest that contrast injection should be performed prior to bone marrow or corticosteroid injection in order to evaluate both the venous drainage of the cyst and its degree of loculation.