Surgical Technique
General endotracheal anesthesia was administered without complication. The patient was positioned supine with a soft bump under her shoulders to place her neck in slight extension and thus facilitate access to the clavicle and great vessels. A 14-cm oblique incision was made over the subcutaneous clavicle extending to the contralateral sternoclavicular joint. Dissection was carried down to the fascia and the biopsy site was excised with the skin paddle. Dissection was carried through the sternocleidomastoid superiorly and the pectoralis major inferiorly, to 8 cm lateral from the right sternoclavicular joint. The clavicle was osteotomized well lateral of the palpable tumor and a marrow margin was sent for frozen section, which was found to be negative.
Dissection was continued circumferentially. Assistance from pediatric general and cardiothoracic surgery was required at the inferior aspect of the mass to assist with exposure and control of the subclavian vein (Figure 5A) . A large branch of the subclavian vein near its junction with the internal jugular vein was found to be involved with the tumor and thus required suture ligation. The subclavian vein was noted to be intimate with the mass and somewhat friable. With the vein mobilized, a cuff of normal tissue was obtained inferiorly and superiorly to the mass. Medially, the sternoclavicular joint was disarticulated (Figure 5B) . At this point, the specimen was delivered from the operative field and tagged in the usual fashion (Figure 5C) . A medial soft tissue margin from the sternal side of the sternoclavicular joint was also sent and found to be negative for tumor. The wound was closed in layered fashion over a ¼” Penrose drain. A soft dressing was placed, and the patient was successfully extubated and transferred to the post-anesthesia care unit in stable condition.
Postoperative Course
The patient was found to be neurologically and vascularly intact on postoperative exam and was discharged on postoperative day 1.
She was seen 14 days postoperatively and was doing well at that time, with full range of motion of the shoulder, elbow, wrist, and hand. Final pathology confirmed a low-grade OS with extraosseous extension. All margins were negative except the medial (sternoclavicular joint) margin and the inferior margin adjacent to the subclavian vein. The intraoperative frozen section from the medial margin was negative for tumor.
The pediatric hematology/oncology team determined that, as no high-grade areas were identified, chemotherapy should be deferred. The positive margins were also discussed with the patient and her family specifically regarding further possible treatments. The findings from the pathology were discussed in a multidisciplinary tumor board and it was felt that, given the low-grade nature of the lesion as well as the high morbidity and risk of mortality with further surgery, additional surgery would be potentially more harmful than helpful. Additionally, low-grade OS is extremely resistant to radiotherapy. The plan remains to monitor her for local recurrence as well as metastases with serial imaging.
Discussion
The clavicle is one of the first bones in the body to ossify but one of the last to have final physeal closure. Its unique characteristics have led to various descriptions, such as a “short tubular bone” versus a “flat bone.” 4,5 Of note are its paucity of a true intramedullary space and scanty red marrow, which make it an unlikely site for a primarily intramedullary- based neoplasm to arise.4 However, it has also been noted that malignant lesions are more common in the clavicle than benign lesions, and special attention should be paid to aggressiveappearing lesions in the clavicle.