title: Endometrioid adenocarcinoma with squamous differentiation arising from ureteral endometriosis in a patient with no history of gonadal endometriosis.
abstract: BACKGROUND
  Malignant transformation may occur in up to 1% of women with endometriosis and only 20% of these cases occur at extragonadal pelvic sites. Similarly, urinary tract endometriosis is rare and occurs in only 1% of all endometriotic lesions.
  
  
  METHODS
  An endometrioid carcinoma with squamous differentiation arising from periureteral endometriosis presented as a pelvic mass encasing the right ureter. The patient had a history of total hysterectomy and bilateral salpingo-oopherectomy 8 years earlier because of bilateral serous benign cysts with right hemorrhagic corpus luteum and uterine fibroids, and has since been under unopposed estrogen replacement therapy for 5 years.
  
  
  CONCLUSIONS
  This is the second case of a malignancy arising in endometriosis presenting as an obstructive ureteral mass and the first case of a patient with this condition whose endometriosis is not consistent with a gonadal origin. An analysis of the case and related literature is presented together with the discussion of possible pathogenetic mechanisms.
authors.affiliation: Division of Gynecologic Oncology, Department of Surgical Pathology, Catholic University of Sacred Heart, Rome, Italy.
authors.forename: M G
authors.initials: MG
authors.lastname: Salerno
authors.forename: V
authors.initials: V
authors.lastname: Masciullo
authors.forename: A
authors.initials: A
authors.lastname: Naldini
authors.forename: G F
authors.initials: GF
authors.lastname: Zannoni
authors.forename: V
authors.initials: V
authors.lastname: Vellone
authors.forename: G
authors.initials: G
authors.lastname: Scambia
mesh_terms: D018269:Carcinoma, Endometrioid / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D002471:Cell Transformation, Neoplastic / Q000473:pathology; D004715:Endometriosis / Q000473:pathology*; D005260:Female; D006801:Humans; D007044:Hysterectomy; D008875:Middle Aged; D014513:Ureter / Q000473:pathology; D014516:Ureteral Neoplasms / Q000473:pathology*