A Large Retroperitoneal Lipoma Manifesting with a Femoral Hernia: A Case Report

Retroperitoneal lipomas are extremely rare findings, with an unknown etiology. Retroperitoneal lipomas are present with different pictures and a variety of symptoms. Diagnosing retroperitoneal lipomas is challenging, due to their rarity, inconclusive histopathological findings, and location. Understanding retroperitoneal lipomas, their presentations, and their nature is essential in managing retroperitoneal sarcomas, to decrease the need for non-justified resection. A 39-year-old female presented to Alexandria Main University Hospital clinic with a soft, reducible mass in the femoral region, below and lateral to the pubic tubercle. A magnetic resonance imaging (MRI) abdomen and a computerized tomography (CT) showed a sizable retroperitoneal lipomatous lobulated soft tissue lesion, measuring 10 cm × 10.8 cm × 24.5 cm. Intraoperatively, a large demarcated fatty tumor was seen adherent to the iliac vessels and extending downward into the femoral triangle. Histopathology revealed a retroperitoneal lipoma. The patient was complicated by a partial femoral nerve injury, that entailed post-operative physiotherapy. Post-operative follow-up continued for 6 months with no signs of recurrence and a remarkable improvement of the neurological mishap. Since 1970, only 30 cases of retroperitoneal lipoma have been reported in the literature. All retroperitoneal masses are assumed to be malignant, as 80% of retroperitoneal masses are malignant. Malignancy is not excluded by imaging techniques like MRI and CT scans, and pre-operative histopathology is almost always inconclusive. Failure to differentiate between benign and malignant retroperitoneal masses, and the absence of a grading system till the present day, R0 resection to all retroperitoneal masses might be the only option.