title: Pelvic malignant hemangiopericytoma mimicking an ovarian neoplasm; a case report.
abstract: BACKGROUND
  Malignant hemangiopericytoma (MHPC) is a rare vascular tumor and has been reported to occur in the musculature of the extremities, retroperitoneum and pelvis. Omental hemangiopericytomas (HPCs) are extremely rare. Synovial sarcomas and solitary fibrous tumors share histologic features with HPCs, causing diagnostic difficulties. Immunohistochemistry is essential for the diagnosis.
  
  
  METHODS
  A 74-year-old woman presented with an abdominopelvic mass. A malignant ovarian tumor was suspected on clinical features, ultrasound and computed tomography. Staging laparotomy revealed a large, vascular tumor adherent to loops of small bowel, colon, cecum and appendix, but the ovaries and uterus were normal. The tumor was completely removed after extensive dissection. Histopathology and detailed immunohistochemistry established the diagnosis of a malignant hemangiopericytoma arising from the omentum. The patient developed recurrent subacute bowel obstruction and died 4 months after the initial diagnosis.
  
  
  CONCLUSIONS
  MHPCs are rare tumors and not likely to be diagnosed preoperatively. Treatment is therefore individualized and based on the findings at laparotomy. Some tumors, such as the one described here, exhibit very aggressive behavior.
authors.affiliation: Department of Obstetrics and Gynaecology, Countess of Chester Hospital, Liverpool Road, Chester, UK. gaityahmad@hotmail.com
authors.forename: Gaity F
authors.initials: GF
authors.lastname: Ahmad
authors.forename: Ram
authors.initials: R
authors.lastname: Athavale
authors.forename: Bushra N A
authors.initials: BN
authors.lastname: Hamid
authors.forename: John
authors.initials: J
authors.lastname: Davies-Humphreys
mesh_terms: D000368:Aged; D003937:Diagnosis, Differential; D017809:Fatal Outcome; D005260:Female; D006393:Hemangiopericytoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D007415:Intestinal Obstruction / Q000209:etiology; D009364:Neoplasm Recurrence, Local; D009367:Neoplasm Staging; D009852:Omentum / Q000473:pathology*; D010051:Ovarian Neoplasms / Q000175:diagnosis*; D010534:Peritoneal Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery