Large mediastinal schwannoma with great vessel encroachment requiring vascular reconstruction: a case report

The most common posterior mediastinal masses are neurogenic tumors such as peripheral nerve sheath tumors (PNST). Schwannomas, a subtype of PNST, are most often benign, well encapsulated tumors of neural crest cell origin, and are frequently incidentally found, ranging in size from small asymptomatic mediastinal tumors to large masses. Rarely, large schwannomas are discovered when symptoms develop due to compression or involvement of nearby structures leading to an array of possible sequela which can include, but not limited to, persistent cough, hemoptysis, and dysphagia. Management decisions are based off of tumor size, location, concern for underlying malignant pathology, and potential for complications related to tumor invasion of vital anatomical structures. A majority of the schwannomas undergo surgical resection, though a subset of small, asymptomatic, benign tumors on imaging or pathology may be managed with surveillance. This case report describes a large posterior mediastinal schwannoma adherent to the posterior aortic arch and encasing the left subclavian and vertebral arteries. Surgical resection required vascular resection of a segment of the left subclavian artery and graft reconstruction using polytetrafluoroethylene (PTFE). This report further highlights the importance of preoperative planning with consideration of a multidisciplinary approach in preparation for resection of large, complex posterior mediastinal masses.