Intrathoracic paraspinal malignant peripheral nerve sheath tumor.

Schwannoma is the most common nerve sheath tumor in the posterior mediastinum, whereas intrathoracic paraspinal malignant peripheral nerve sheath tumor (MPNST) is quite rare. Both benign and malignant nerve sheath tumors may be symptomatic, rendering clinical differentiation of limited utility. On radiographic imaging, erosion of the ribs and vertebral bodies, irregularity in contour, and inhomogeneity in attenuation are not sufficiently reliable for diagnosis of MPNST. Histologically, MPNSTs reveal hypercellularity, nuclear atypia, and mitotic activity. Surgical resection is the main modality of treatment. Postoperative radiation therapy for MPNST has led to a significant reduction in local recurrence. The prognosis is unfavorable. Herein, we present an unusual case of a posterior mediastinal mass in a 50-year-old female with delayed diagnosis of 2 years. After surgical intervention, the histologic finding was MPNST. Postoperative radiation therapy was applied because of incomplete resection. The follow-up chest computed tomography 5 months later revealed a residual soft tissue mass with significant reduction in size over the parathoracic spine area. No neurologic sequelae were identified after surgery.