A rare case of asymptomatic retroperitoneal and thigh femoral nerve schwannoma.

We present a rare case of an asymptomatic extensive tumor in the retroperitoneum and thigh, which has not been published in the scientific literature so far. During the preventive examination, in an otherwise healthy 29-years old man, a tumor mass in the lower left abdominal quadrant was observed on ultrasound. A computed tomography scan and magnetic resonance imaging revealed a large, lobulated, multiseptated retroperitoneal mass stretching from the level of the lower left kidney pole to the distal third of the left thigh. Positron emission tomography/ computed tomography showed weak metabolically active mass with low probability of malignancy, and radiological differential diagnosis included lymphangioma, less likely lymphoma and as least likely sarcoma. Due to the assumed liquid content of the tumor, no preoperative biopsy was performed. A demanding and long-lasting operation was performed on Department of abdominal surgery at Clinical Hospital Merkur. The tumor was removed completely along with most part of the femoral nerve. Pathohistological analysis showed a benign tumor of the nerve sheath- schwannoma. A novel aspect in the presentation of this clinical entity is the extensiveness of the neoplasm to multiple regions without symptoms. According to the available literature, only 2 similar case reports are described, which were symptomatic.