Preoperative diagnosis of middle mediastinal vagal schwannoma enabling nerve preservation: a case report.

Middle mediastinal schwannomas are rare and can mimic malignant mediastinal tumours, making preoperative diagnosis challenging. A 52-year-old woman presented with persistent cough refractory to medical treatment. Chest computed tomography revealed a well-defined 35 × 26 mm mass in the right middle mediastinum, and 18F-fluorodeoxyglucose positron emission tomography showed increased uptake with a maximum standardized uptake value of 8.8. Endobronchial ultrasound-guided transbronchial needle aspiration was performed, and histological examination revealed S-100-positive spindle-shaped cells with a low Ki-67 labeling index, leading to a diagnosis of schwannoma. Based on the tumour location and pathological diagnosis, the cough was considered attributable to vagal nerve irritation. Thoracoscopic tumour resection was performed with careful preservation of the vagal nerve. The cough resolved promptly after surgery, and no recurrence was observed during 1 year of follow-up. Preoperative pathological diagnosis was useful for planning a nerve-preserving surgical strategy.