title: Transition of endometrial stromal sarcoma into high-grade sarcoma.
abstract: BACKGROUND
  Endometrial stromal sarcoma typically is of low grade and hormone-sensitive. Although these characteristics result in an indolent behavior, little data are available on the evolution over time.
  
  
  METHODS
  We report on two cases where microscopic and immunohistochemic assessment of the tumor on several occasions during 8 and 25 years of follow up enabled us to document a transition of a low-grade into a high-grade malignancy. These were mainly characterized by increased cellular atypia, absence of spiral arterioles and an increased mitotic index and proliferation index (MIB1). Since this transition was related to clinical loss of hormone sensitivity, the therapeutic approach consisting of hormonal treatment in combination with repetitive surgery was switched to chemotherapy only.
  
  
  CONCLUSIONS
  These long-term follow up data provide insight in endometrial stromal sarcoma tumor biology and highlight the importance of sampling recurrent tumors to estimate biologic behavior in order to tailor subsequent treatment.
authors.affiliation: Division of Gynecological Oncology, Department of Obstetrics and Gynecology, UZ Gasthuisberg, Katholieke Universiteit Leuven, Herestraat 49, 3000 Leuven, Belgium. Frederic.amant@uz.kuleuven.ac.be
authors.forename: Frederic
authors.initials: F
authors.lastname: Amant
authors.forename: Heidi
authors.initials: H
authors.lastname: Woestenborghs
authors.forename: Vanessa
authors.initials: V
authors.lastname: Vandenbroucke
authors.forename: Patrick
authors.initials: P
authors.lastname: Berteloot
authors.forename: Patrick
authors.initials: P
authors.lastname: Neven
authors.forename: Philippe
authors.initials: P
authors.lastname: Moerman
authors.forename: Ignace
authors.initials: I
authors.lastname: Vergote
mesh_terms: D000328:Adult; D002471:Cell Transformation, Neoplastic; D003131:Combined Modality Therapy; D003937:Diagnosis, Differential; D016889:Endometrial Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D005260:Female; D006801:Humans; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D018203:Sarcoma, Endometrial Stromal / Q000175:diagnosis* / Q000473:pathology / Q000628:therapy; D017154:Stromal Cells