A rare cause of femoral neuropathy: Giant cell tumor mimicking a femoral nerve sheath tumor

Abstract

Femoral neuropathy is an uncommon peripheral neuropathy typically caused by compression, trauma, or iatrogenic injury, while tumor-related involvement is rare. Giant cell tumors are mesenchymal lesions that rarely involve peripheral nerves and may mimic nerve sheath tumors on imaging, creating diagnostic challenges. We report a 33-year-old woman presenting with a two-month history of progressive right thigh pain, weakness, and muscle atrophy, initially misdiagnosed as a musculoskeletal condition without improvement on conservative therapy. Neurological examination revealed mild weakness (MRC 4/5) and reduced patellar reflex, while electrodiagnostic studies confirmed femoral neuropathy. Pelvic magnetic resonance imaging (MRI) demonstrated a well-defined ovoid lesion (0.7 × 1.3 × 3.1 cm) along the right femoral nerve, initially suspected to be a nerve sheath tumor. The patient underwent surgical tumor debulking, and histopathological as well as immunohistochemical analysis (positive for smooth muscle actin, vimentin, and CD68) confirmed giant cell tumor. Postoperatively, the patient showed improvement in neuropathic pain with gradual motor recovery. This case highlights a rare cause of femoral neuropathy and underscores the importance of a comprehensive diagnostic approach integrating clinical evaluation, electrodiagnostic studies, imaging, and histopathology to ensure accurate diagnosis and appropriate management.