Giant retroperitoneal lipoma (MDM2 negative) in a young patient

Abstract

The mesenchymal solid retroperitoneal lesions are uncommon, representing less than 1%. Liposarcomas constitute 10 to 15% of the retroperitoneal sarcomas, which represent the first differential diagnosis of benign lipomas. The immunohistochemistry, specifically the MDM2, give the accurate histological diagnosis, where their negativity translates into benignity. The treatment of choice is surgical R-0 resection. Clinical case: We report the case of 24 years old female patient who refers five months before admission increased abdominal girth and pain, predominantly at the left flank. Clinical and laboratory tests indicate presumptive diagnosis of retroperitoneal fatty tumor. Exploratory laparotomy is done with the findings of large retroperitoneal lipomatous tumor. R-0 resection of the lesion is performed without complications. Operating time: 110 minutes, estimated blood loss: 150 cc. Fatty tumor aspect of 11 kg and 55 cm. The patient’s progress was satisfactory and he was discharged on the second postoperative day. Mature adipose tissue biopsy reports without atypia. Lipomatous tumor immunohistochemistry reports, MDM2 negative, discarding liposarcoma diagnosing. Conclusion: We conclude that the giant retroperitoneal lipomas corresponds a rare condition. The surgical resolution is based on R-
0 resection, and the MDM2 allow a reliable histological diagnosis  and thus will provide the surgeon with the capacity to decide the post-operative treatment.