Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 52 9 2014 09 15 717 720 EN Hayedeh Haeri Department of Pathology, Cancer Institute, Imam Khomeini Medical Complex, Tehran, Iran. Babak Vosooghi Department of Pathology, Cancer Institute, Imam Khomeini Medical Complex, Tehran, Iran. Fahimeh Asadi Amoli Department of Pathology, Farabi Hospital, Tehran, Iran. 2015 10 11 Primary retroperitoneal mucinous tumor (PRMT) of low malignant potential (border line) is an uncommon neoplasm with fewer than 50 reported cases. Uncertain diagnostic imaging results make diagnosis of its origin difficult, preoperatively. Later treatment planning and prognosis would be affected by exact diagnosis of the tumor origin. This study presents a case of Persian woman with diagnostic, histological and immunohistochemical specifications. https://acta.tums.ac.ir/index.php/acta/article/view/4653 https://acta.tums.ac.ir/index.php/acta/article/download/4653/4636