Mediastinal Schwannoma: a case report

Abstract

Posterior mediastinal tumors are most commonly neurogenic in origin, and schwannomas account for the majority of these lesions. Schwannomas are benign, encapsulated tumors arising from peripheral nerve sheaths that typically remain asymptomatic until they attain large dimensions or compress adjacent structures. We report the case of a 46-year-old woman with a history of progressive lower-limb weakness, lumbar pain, and paresthesia. Imaging revealed a large thoracic expansile mass involving the T2 vertebral body, measuring approximately 7.5 × 7.1 × 7.0 cm, causing spinal cord compression with signal changes consistent with spinal cord edema (Fig 1–4).  The patient underwent a combined neurosurgical and thoracic surgical approach, beginning with laminectomy and biopsy. Histopathological examination initially suggested a low-grade spindle-cell mesenchymal proliferation compatible with aggressive fibromatosis/desmoid tumor; however, immunohistochemistry demonstrated negativity for pancytokeratins and beta-catenin and positivity for S-100 protein, establishing a profile consistent with soft-tissue schwannoma. Complete surgical resection was subsequently performed, with careful dissection from adjacent mediastinal structures, followed by thoracic spine arthrodesis. The patient had a favorable postoperative course, with improvement in motor strength and lumbar pain. This case underscores the importance of multimodal imaging, thorough histopathological analysis including immunohistochemistry, and a multidisciplinary surgical approach in the management of large posterior mediastinal schwannomas with spinal canal involvement.