%0 Journal Article %T Retroperitoneal Extraskeletal Osteosarcoma in a Pregnant Woman Incidentally Found on Cesarean Section %A Shizue Fujihara %A Teruyuki Yamasaki %A Kontoku Shimokawa %A Han-Seung Yoon %J Open Journal of Pathology %P 14-18 %@ 2164-6783 %D 2016 %I Scientific Research Publishing %R 10.4236/ojpathology.2016.61003 %X Extraskeletal osteosarcoma (ESO) is a rare malignant mesenchymal neoplasm accounting for 1% - 2% of all soft tissue sarcomas that produce osteoid, bone, and/or chondroid material. Here we report the first case of a retroperitoneal ESO in a 35-year-old pregnant woman. A retroperitoneal ESO was incidentally found at cesarean section. Despite treatment, she rapidly died from wide spread dissemination. We focus on histological characteristics including immunohistochemical results and differential diagnosis of ESO. %K Extraskeletal Osteosarcoma %K Pregnant Woman %K MDM2 %K CDK4 %U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=62654