Mediastinal Schwannomas at Conventional Lymph Node Stations: Diagnostic Pitfalls and Surgical Implications in Two Cases

Background A mediastinal mass located within a conventional lymph node station is not necessarily lymph node-derived. When the lesion may arise from an adjacent mediastinal nerve, the distinction has implications for exposure, nerve identification, and nerve preservation. Case presentation A 63-year-old woman had a 2.6 × 1.8 cm mass in the aortopulmonary window (station 5) with heterogeneous contrast enhancement. Left video-assisted thoracoscopic resection showed origin from the left vagus nerve; complete excision was achieved while preserving nerve continuity. A 68-year-old man undergoing coronary evaluation had a 4.0 × 3.5 cm mass posterior to the superior vena cava across the anatomical regions corresponding to stations 2R and 4R, with moderate heterogeneous enhancement and no conspicuous enlarged or tortuous vessels. The mass was completely resected through the same median sternotomy after coronary artery bypass grafting; its nerve of origin could not be identified. Both tumors were histologically confirmed as schwannomas, and neither specimen contained lymph node tissue or recognizable nodal architecture. Conclusions A lymph node station should be used for anatomical localization, not as proof of tissue origin. If enhancement is not typical of a markedly hypervascular nodal lesion, feeding vessels are not conspicuous, or a neural relationship is possible, schwannoma should remain in the differential diagnosis. This recognition may support safer individualized exposure and nerve-aware dissection.