Metastatic High-Grade Osteosarcoma with Direct Extension into the Left Atrium: Resection Combined with Right Middle Lobectomy

The Patient

A twenty-two-year-old man with a history of a left distal femur high grade osteosarcoma underwent a previous limb salvage procedure for the osteosarcoma followed by adjuvant chemotherapy. Recent surveillance, however, revealed a right lung mass that seemed to involve the right middle lobe. A chest X-ray showed a mass in the right hemithorax that abutted the right cardiac border. A chest CT scan showed a right lung mass that was both occupying the majority of the right middle lobe and abutting the right side of the pericardium. There was evidence of extension or invasion of the mass to the right middle lobe pulmonary vein and the left atrium. No other lung masses were found and no mediastinal lymphadenopathy was detected.

A transesophageal echocardiogram revealed a large mobile pedunculated mass in the left atrium that measured nearly 11 x 40 mm. The mass appeared attached to or coming through the right upper pulmonary vein; but there was no mitral valve inflow obstruction. Both right and left ventricles were of normal chamber size, thickness, and systolic function.

Given the risk of systemic embolization and the size of the mass (and in absence of any other metastases), the decision was made to proceed with resection of the mass combined with right middle lobectomy. The plan was to proceed through a standard median sternotomy and using cardiopulmonary bypass.

The Surgery

Through a standard median sternotomy, the right pleural space was opened, and the large mass occupying the right middle lobe was identified. It was adherent to the lower portion of the right side of the pericardium. Via aortic and right atrial cannulation, cardiopulmonary bypass was initiated without difficulty at normothermia. Once cardioplegic arrest was achieved, a standard vertical left atriotomy was performed, and the large left atrial mass was easily visualized. It extended to the inflow of the mitral valve—without actual invasion into any of the intracardiac structures.

Next, the inferior pulmonary ligament was divided, and the right lung was freed up. The right lung hilum was then dissected, and all of the right middle lobar vascular and bronchial structures were identified, ligated, and divided in the standard fashion for a right middle lobectomy. The lower portion of the right-sided pericardium was resected as well due to being involved with the tumor. Then, the pulmonary vein containing the mass was dissected and isolated. A venotomy was performed and extended along the vein until the intracardiac portion. Working on both sides of the pericardium facilitated resection of the mass in a controlled fashion without any part of the tumor breaking off. 

After this, the mass was gently pulled out of the left atrium. The pulmonary vein was then divided, and the right middle lobe and the tumor were removed in one piece. The left atriotomy was then closed with a running 3-0 Prolene suture in a single layer fashion. The heart was then deaired, and the aortic cross clamp was removed. The patient regained his normal sinus rhythm quickly. Surgeons then used a piece of bovine pericardium to reconstruct the removed portion of the right-sided pericardium. It was sewn in using a running 3-0 Prolene suture, paying attention to the very nearby right phrenic nerve. The patient, in the meantime, was ventilated and weaned off cardiopulmonary bypass without difficulty. All cannulas were then removed, and the cannulation sites were secured with additional Prolene sutures. The rest of the procedure was then completed in a routine fashion.

The aortic cross clamp time was fifty-five minutes, and the cardiopulmonary bypass time was sixty-three minutes. The patient was extubated in the operating room, and the remainder of his postoperative course was uneventful. He was discharged on postoperative day three.

A predischarge echocardiogram showed no residual mass in the left atrium. The right and left ventricles were of normal chamber size, thickness, and systolic function, and there was a trivial mitral valve regurgitation. The postoperative CT showed no evidence of residual disease.

References

1. Reisenauer JS, Said SM, Allen MS. Metastatic Rectal Adenocarcinoma Presenting as a Giant Left Atrial Mass: Resection Combined With Right Lower Lobectomy. Ann Thorac Surg. 2016 Jul;102(1):e19-21
2. Madison MK, Matthews CR, Lee LS. Intracardiac extension of chondroblastic osteosarcoma. Interact Cardiovasc Thorac Surg. 2021 Jan 1;32(1):159-160
3. Metastatic cardiac osteosarcoma–imaging features. Atra A, Shankar AG, Padhani AR. Br J Radiol. 1998 Mar;71(843):336-9

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