(P 299) PULMONARY METASTASECTOMY OF OSTEOSARCOMA VIA PNEUMONECTOMY AND MEDIAN STERNOTOMY WITH COMPLETE INTRATHORACIC LIVER MIGRATION: A CASE REPORT

Objective: Pulmonary metastasectomy is the well-accepted surgical management for resectable metastatic osteosarcoma, majority of which involves a wedge resection or lobectomy. A pneumonectomy, with its high mortality and morbidity rate, is seldom performed for a metastasectomy, even more so via sternotomy. We report an unusual case of pneumonectomy via median sternotomy for metastatic osteosarcoma with complete migration of the liver into the postpneumonectomy space, a complication rarely observed.

Methods: A 58-year-old female with a history of osteosarcoma arising from the right proximal humerus was initially treated with neoadjuvant chemotherapy, resection and endoprosthetic reconstruction of the humerus, and a pedicled latissimus dorsi flap reconstruction. Four years later, a right middle lobectomy was performed for a metastasis, with histologically clear margins and no nodal involvement. Ten years following the lobectomy, she presented with a new cough. Computed tomography revealed a right hilar lobulated mass, measuring 7.1 cm x 5.6 cm x 5.9 cm, posteriorly displacing the right main bronchus (Figure 1). Positron-emission tomography showed significant uptake and an endobronchial ultrasound biopsy confirmed metastatic osteosarcoma. An en bloc intrapericardial right completion pneumonectomy and mediastinal lymph node dissection was performed via median sternotomy. Two factors favoured this unconventional approach: the hostile hilum subjected to a previous lobectomy and avoiding injury to the pedicled latissimus dorsi flap used for the initial reconstruction. Histologically, the solitary tumour was well-circumscribed and un-encapsulated with atypical spindle cells in intersecting fascicles (Figure 2). Hyperchromasia, pleomorphism, nuclear atypia and high mitotic indices were demonstrated. Osteoid with calcification was present, confirming osteosarcoma.

Results: On postoperative follow-up imaging, the liver migrated into the thoracic cavity completely (Figure 3), a rarely observed phenomenon in clinical practice. The patient had a disease-free interval of four and ten years between recurrence. She has been asymptomatic and disease-free on follow up, 21 years following the initial diagnosis.

Conclusion: Aggressive approaches for pulmonary metastasectomy, despite clinician hesitation in the age of minimally invasive surgery, can yield excellent outcomes. This case highlights extended indications of a median sternotomy approach, including metastasectomy that is in close proximity to the hilum or that which requires intrapericardial dissection. While a pneumonectomy carries significant morbidity and mortality, this approach, in our selected patient, has produced a 21-year survival from diagnosis and exceptional quality of life, for an aggressive cancer with otherwise poor prognosis.