Giant retroperitoneal solitary neurofibroma.

Solitary, benign retroperitoneal neurofibromas are exceedingly rare. Our case report highlights a man who presented with left-sided abdominal pain and left lower extremity numbness and weakness. On cross-sectional imaging, a 12.1 cm × 9.8 cm × 7.5 cm lobulated, well-marginated mass emanating from the left iliopsoas muscle at the level of the pelvic rim was visualised. A tissue biopsy suggested the diagnosis of a neurofibroma. The patient underwent resection of a femoral nerve sheath tumor, which resulted in femoral nerve palsy. Subsequent distal reconstructive surgeries and physical therapy resulted in improvement of his postoperative deficits. This is a highly rare case of a giant retroperitoneal solitary neurofibroma of the femoral nerve sheath diagnosed in a young patient.