Intrathoracic Vagal Schwannoma Mimicking Metastatic Lymphadenopathy with a Positional Shift.

INTRODUCTION: Schwannomas are benign tumors originating from peripheral nerve sheaths and are most commonly found in the head, neck, and extremities. Intrathoracic schwannomas, particularly those arising from the vagus nerve, are relatively rare. Despite their benign nature, schwannomas often exhibit fluorodeoxyglucose (FDG) uptake on PET scans, potentially leading to diagnostic confusion. This report presents a case initially suspected to be a metastatic lymph node but later diagnosed as a schwannoma from the intrathoracic vagus nerve, highlighting the diagnostic challenges associated with thoracic nodal lesions.

CASE PRESENTATION: A 36-year-old woman with a history of cryptogenic optic neuritis presented with a posterior mediastinal nodule discovered on chest CT. FDG-PET/CT revealed uptake in the nodule, initially raising suspicion of metastatic lymphadenopathy. A repeat CT scan showed that the nodule had shifted medially, suggesting a pedunculated lesion rather than lymphadenopathy. Thoracoscopic findings revealed a 2-cm nodule arising from the vagus nerve and exhibited mobility due to its pedunculated growth. The tumor was enucleated, preserving the main nerve trunk. Histopathological examination confirmed the diagnosis of schwannoma.

CONCLUSIONS: Schwannomas originating from the thoracic vagus nerve can exhibit pedunculated growth and positional migration, posing diagnostic challenges. Mobile mediastinal nodules should prompt consideration of vagal nerve schwannomas in the differential diagnosis. Recognizing that benign schwannomas can accumulate FDG on PET scans is crucial to avoid misdiagnosis as malignancy. This case underscores the importance of comprehensive imaging analysis and clinical correlation in the evaluation of mediastinal masses, potentially alleviating unnecessary psychological burden on patients due to the suspicion of malignancy.