Resection of a rare lumbar epithelioid schwannoma.

Background: Schwannomas, along with meningiomas, constitute the most common type of intradural extramedullary tumors. They are rare, typically benign tumors that originate from Schwann cells. Symptoms and signs attributed to these tumors may include back/radicular pain, focal motor and/or sensory deficits, and bowel/bladder dysfunction. It is essential to obtain pathological confirmation of this lesion and to differentiate it from other benign (i.e., neurofibromas, lipomas, ganglion cysts, meningiomas, and giant cell tumors), and/ or infrequently malignant lesions (i.e., malignant peripheral nerve sheath tumors, and sarcomas). Epithelioid Schwannomas/Benign Epithelioid Schwannomas (BES) is a benign, rare histologic subtype of schwannoma that resembles epithelial cells and lacks classic features such as Antoni A and Antoni B areas.

Case description: A 29-year-old female presented with 1 year of severe, constant, sharp back pain (i.e., 5-10/10) that radiated down the left lower extremity. She also experienced bilateral leg numbness and tingling, along with weakness in the hips and right lower extremity. Diclofenac failed to provide any pain relief. Notably, symptoms progressed despite the utilization of physical therapy. Her neurological examination showed mild weakness (4+/5) in the left tibialis anterior and extensor hallucis longus distributions. The magnetic resonance imaging revealed a heterogeneously enhancing circumferential intradural extramedullary mass at the L2 level that caused cauda equina compression. The patient underwent an L1-L2 laminectomy, which was recommended for tumor resection. Pathologically, the lesion proved to be a BES; the epithelial cells stained positive for S-100. Three months postoperatively, the patient is asymptomatic.

Conclusion: BES is a rare subtype of schwannoma. Patients with these lesions should undergo gross total tumor resection to achieve the best long-term postoperative outcomes.