Mediastinal schwannoma with cystic changes mimics malignancy on PET, EBUS-TBNA non-diagnosticMultimodal Imaging Helps Identify Benign Mediastinal Schwannoma in Patient

Schwannomas represent the most common neurogenic tumors of the posterior mediastinum. Although typically slow-growing and asymptomatic, degenerative changes such as cystic transformation may alter their imaging appearance and mimic necrotic lymphadenopathy or malignant mediastinal masses. A 61-year-old man underwent chest CT for respiratory symptoms. Careful image review revealed an incidental subcarinal mediastinal lesion initially suspected to represent necrotic lymphadenopathy. Further evaluation with contrast-enhanced CT, 18F-FDG PET/CT and endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) was performed. PET imaging demonstrated moderate FDG uptake while EBUS-TBNA cytology was non-diagnostic. Progressive enlargement of the lesion and the onset of compressive symptoms led to surgical resection. Histopathological examination confirmed a benign mediastinal schwannoma with cystic degenerative changes. This case highlights the diagnostic pitfalls associated with mediastinal schwannomas and underscores the complementary role of multimodal imaging and multidisciplinary assessment in the diagnostic work-up of a mediastinal lesion.