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Findings: CT examination reveals a large soft tissue mass adjacent to the right scapula. This soft tissue mass arises from the bone. The scapula is irregular in appearance demonstrating a predominately lytic pattern of destruction. The patient was to undergo operative resection of this mass, and preoperative embolization was requested to minimize blood loss. Selective catheterization of the axillary artery revealed that the primary blood supply to the mass arose from a hypertrophied branch of the axillary artery, identified as subscapular artery. Successful embolization was facilitated using multiple embolic coils.
Diagnosis: Renal cell cancer with right scapular metastases and successful preoperative therapeutic embolization.
Discussion: Bony metastases of renal cell cancer are typically lytic and expansile in appearance. As a rule renal cell metastasis tend to be vascular. Preoperative embolization has been used to reduce blood loss during resection of vascular bone tumors such as metastatic renal cell carcinoma.
Superselective catheterization technique is necessary to limit embolization of embolic material to adjacent structures. Selection of the embolic agent is dependent on the proximity of the embolization procedure to surgery. If surgery is to immediately follow therapy, an absorbable agent such as gelfoam or proximal coil embolization can be substituted. If the surgical procedure is delayed, recanalization of the occluded vessel, and/or development of peripheral collateral blood flow, may occur. In cases where surgery will be delayed, a nonresorbable agent such as Ivalon particles can be used to facilitate peripheral embolization which will minimize risks of recanalization or collateral vessel formation. In preoperative cases such proximal coil embolization is utilized, since the cases are arranged to occur the evening before surgery in our institution.
Embolization of benign bone tumors has also been employed for the palliation of pain. In these cases, permanent agents should be used to ensure prevention of revascularization or the development of distal collaterals.
Complications of embolization therapy include a post-embolization syndrome of pain, fever, and increased WBC count in approximately 40% of patients undergoing embolization. This usually resolves in 48-72 hours. PCA analgesia is used to manage pain during and after embolization. Infection of the embolized area may also occur. This is easily treated with antibiotics and the risk minimized by use of preprocedure antibiotic prophylaxis. Embolization of contiguous vessels must be minimized by use of superselective technique to ensure embolization of the target vessel. Constant check of catheter position and slow deliberate delivery of embolic agents is imperative. Care must be taken to minimize catheter recoil and pre-embolization test injections should be carried out.
A complete discussion of embolic agents, catheters and technique is beyond the scope of this discussion, and the viewer is referred to Castaneda, et al, Interventional Radiology (Ref #1).
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