Case Report: Spectral CT characterization of giant esophageal schwannoma with reactive lymphoid hyperplasia mimicking lymphoproliferative disease.

Esophageal schwannoma is an uncommon mesenchymal tumor that is frequently misdiagnosed before surgery because its clinical and radiological appearances overlap with those of other submucosal esophageal tumors and mediastinal masses. We report a 48-year-old woman with mild dysphagia and an incidentally detected right mediastinal mass. Spectral computed tomography (CT) demonstrated an 83 × 63 × 100 mm upper-to-middle thoracic esophageal submucosal mass with an intraluminal air crescent sign, heterogeneous enhancement, and multiple enlarged mediastinal and perigastric lymph nodes. Compared to conventional contrast-enhanced CT, low-energy 45-keV monoenergetic images and iodine-based spectral parameters yielded higher absolute attenuation values, objectively characterizing the heterogeneous intratumoral enhancement and demonstrating spectral differences between the primary mass and lymph nodes. Endoscopy confirmed a long submucosal elevated lesion with a localized ulcer, bronchoscopy showed extrinsic airway compression, and barium esophagography revealed a smooth filling defect. Partial esophagectomy was performed because of the tumor size and its proximity to an aberrant right subclavian artery and the brachiocephalic trunk. Due to the unachievable complete en bloc resection, the macroscopic residual mass was successfully managed with targeted adjuvant radiotherapy. Histopathology revealed a spindle-cell tumor with a prominent peripheral lymphoid cuff. To avoid diagnostic ambiguity, immunohistochemical profiling was stratified: the spindle cells were positive for S-100 and vimentin, and negative for SMA, desmin, and DOG-1, which confirmed schwannoma and excluded gastrointestinal stromal tumor. The surrounding reactive lymphoid component specifically exhibited B-cell markers.