title: A case of retroperitoneal liposarcoma after delivery with expression of estrogen receptor: Report of a case.
abstract: BACKGROUND
  Liposarcoma is one of the most common soft tissue sarcomas; however, early diagnosis is rare as the tumor remains difficult and unpalpable for a prolonged period of time.
  
  
  METHODS
  Here we report the first case of retroperitoneal liposarcoma associated with pregnancy and expression of estrogen receptor. A 34-year-old woman experienced persistent abdominal distension after her first delivery. Computed tomography (CT) and magnetic resonance imaging (MRI) revealed a large (40cm×35cm), solid, palpable abdominal mass with fat attenuation displacing the ascending colon and the right kidney to the left. Laparotomy and an en-bloc resection of the tumor were performed; further, right nephrectomy and adrenalectomy were required. Histopathology showed a well-differentiated liposarcoma; approximately 10-20% of the tumor cells were ER-positive.
  
  
  CONCLUSIONS
  Retroperitoneal liposarcoma associated with pregnancy is an extremely rare occurrence. Surgical resection is unquestionably the first choice of treatment, but complete resection is sometimes impossible due to the volume and depth of invasion of the tumor. In such cases, additional therapy for liposarcoma is important to improve prognosis. Thus, this report highlights the need for further research into hormone therapy.
  
  
  CONCLUSIONS
  Retroperitoneal liposarcoma has a high local recurrence rate due to the difficulty in complete surgical resection; therefore, additional hormone therapy is important for improving the prognosis.
authors.affiliation: Department of Surgical Oncology, Osaka City University Graduate School of Medicine, 1-4-3 Asahi-machi, Abeno-ku, 545-8585 Osaka, Japan. Electronic address: m1165063@med.osaka-cu.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kasashima
authors.affiliation: Department of Surgery, Japan Community Healthcare Organization Osaka Hospital, Osaka, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Yamasaki
authors.affiliation: Department of Surgery, Japan Community Healthcare Organization Osaka Hospital, Osaka, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Morimoto
authors.affiliation: Department of Surgery, Japan Community Healthcare Organization Osaka Hospital, Osaka, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Akamaru
authors.affiliation: Department of Surgery, Japan Community Healthcare Organization Osaka Hospital, Osaka, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Yasumasa
authors.affiliation: Department of Pathology, Japan Community Healthcare Organization Osaka Hospital, Osaka, Japan.
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Kasugai
authors.affiliation: Department of Pathology, Japan Community Healthcare Organization Osaka Hospital, Osaka, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Yoshida
keywords: Estrogen receptor; Pregnancy; Retroperitoneal liposarcoma