en Oncology Oncology case report case report <div> <div> <div id="_com_1" uage="JavaScript"><span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="color:#0000ff;"><strong><em>Background</em></strong><em>:</em></span> Lipoma is a benign mesenchymal tumor of soft tissue that occurs in almost all parts of the body where fat normally exists. Retroperitoneal lipomas are very infrequent condition with about 20 cases represented in the literature since 1980. They usually present as an abdominal mass or with pressure symptoms to adjacent organs.<br> <span style="color:#0000ff;"><strong><em>Case Presentation</em></strong><em>:</em> </span>A 66-year-old, post-menopausal woman referred to Imam Hossein Medical Center due to abdominal pain. Abdominopelvic magnetic resonance imaging (MRI) revealed a large mass containing fat component without enhancement on the right side of the pelvis. Tumor markers were within normal ranges. The patient underwent laparotomy and a 12 cm retroperitoneal mass which was located on the iliopsoas muscle with extension into the inguinal canal was resected with pathology report of lipoma. There has been no recurrence after one year of follow-up since surgery.<br> <span style="color:#0000ff;"><strong><em>Conclusion</em></strong><em>:</em> </span>In the differential diagnosis of retroperitoneal pelvic mass at all ages, lipoma should be considered as a rare cause.</span></span></div> </div> </div> Retroperitoneal lipoma, Pelvic mass, Fatty Tumor 495 499 http://caspjim.com/browse.php?a_code=A-10-2071-1&slc_lang=en&sid=1 Maliheh Arab drmarab@sbmu.ac.ir 100319475328460031285 100319475328460031285 Yes Department of Gynecology Oncology, Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Somayyeh Noei Teymoordash noeiteymoordash.s@sbmu.ac.ir 100319475328460031286 100319475328460031286 No Department of Gynecology Oncology, Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Maryam Talayeh m_talayeh@yahoo.com 100319475328460031287 100319475328460031287 No Department of Gynecology Oncology, Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Abdolali Ebrahimi ebrahimibeheshti@gmail.com 100319475328460031288 100319475328460031288 No Department of Pathology, Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Niloofar Nakhlian n.nakhlian@yahoo.com 100319475328460031289 100319475328460031289 No Department of Obstetrics and Gynecology, Imam Hossein Medical Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Narges Khatoon Tabatabaei Shoja ntabatabaeishoja@gmail.com 100319475328460031290 100319475328460031290 No Department of Obstetrics and Gynecology, Shahid Sadoughi University of Medical Sciences, Yazd, Iran Masoomeh Raoufi masomeraoufi@gmail.com 100319475328460031291 100319475328460031291 No Department of Radiology, Imam Hossein Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran