title: Synchronous and metachronous retroperitoneal sarcomas: two case reports.
abstract: BACKGROUND
  Retroperitoneal sarcomas represent less than 1% of all diagnosed human neoplasias. They are generally malignant and can infiltrate retroperitoneal structures. The value of chemotherapy and radiotherapy are difficult to evaluate and the dominating factor in the outcome is the ability to resect the tumor. A few patients develop distant metastases. Recurrence of sarcoma at the operative site and on peritoneal surfaces is a prominent cause of morbidity and mortality.
  
  
  METHODS
  Here we report two patients who underwent surgery for retroperitoneal sarcoma. In each of them at least two primary retroperitoneal tumors were diagnosed. The neoplasms were histologically different, thus they cannot be considered local recurrence but rather primary tumors.
  
  
  CONCLUSIONS
  This is the first report underlying the synchronous or metachronous presence of different histological subtypes in this neoplastic pathology. In explanation of the occurrence of satellite tumors and multiple primary tumors, a virus-associated etiology or polyclonality of the tumor or pluripotentiality of tumor stem cells should be considered.
authors.affiliation: Department of Surgery Pietro Valdoni, School of Medicine, University of Rome La Sapienza, Italy. paolo_aurello@yahoo.it
authors.forename: P
authors.initials: P
authors.lastname: Aurello
authors.forename: C
authors.initials: C
authors.lastname: Cicchini
authors.forename: R
authors.initials: R
authors.lastname: De Angelis
authors.forename: F
authors.initials: F
authors.lastname: D'Angelo
authors.forename: G
authors.initials: G
authors.lastname: Ramacciatos
authors.forename: S
authors.initials: S
authors.lastname: Valabrega
authors.forename: M
authors.initials: M
authors.lastname: Indinnimeo
mesh_terms: D000368:Aged; D005260:Female; D006801:Humans; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D016609:Neoplasms, Second Primary / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D011859:Radiography; D012186:Retroperitoneal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D012509:Sarcoma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*