Giant thymoma presenting as a large bilateral intrathoracic mass: A case report and a comparison between median sternotomy and hemiclamshell approach

INTRODUCTION: Thymoma is an epithelial tumor that commonly lies in the anterior mediastinum. It rarely extends to the pleural cavities. There is no standard approach for resecting similar giant thymomas. CASE PRESENTATION: An eighteen-year-old woman presented with a six-month history of progressive exertional dyspnea, weight loss, and loss of appetite. Radiological imaging demonstrated a giant mediastinal mass extending to both pleural cavities, a transthoracic needle biopsy was then performed, which indicated thymic hyperplasia. CLINICAL DISCUSSION: The tumor was completely resected using a two-step approach, starting with a median sternotomy then extending it to a hemiclamshell incision, which provided better exposure of the tumor and caused less morbidity. The left part of the thymoma was resected using a median sternotomy, which took a relatively long time and caused significant blood loss. Then the incision was extended to a hemiclamshell incision through the pleural cavity to remove the right part of the tumor. This approach helped us to visualize the tumor better and did not cause any significant blood loss. The removed mass measured 36 × 29 × 10 cm and weighed 4500 g. Pathologic diagnosis indicated a type B1 tumor with no capsular invasion according to the World Health Organization classification. CONCLUSION: The hemiclamshell approach is superior to the median sternotomy incision in resecting giant thymomas extending to the pleural cavity, as it saves time and causes less morbidity.