title: A peculiar case report of extraovarian Brenner tumor arising in the omentum.
abstract: BACKGROUND
  Brenner tumors almost always develop in the ovary. Exceptionally, extraovarian Brenner tumors have been reported in the lower abdomen or pelvic organs. Here, we introduce a peculiar case of an extraovarian Brenner tumor arising in the omentum.
  
  
  METHODS
  A 43-year-old woman presented with a palpable abdominal mass. Computed tomography (CT) scan revealed a 9.0-cm solid mass in the omentum. The tumor was not associated with pelvic structures, including the ovaries. It was excised under the clinical impression of an extragastrointestinal stromal tumor or neurogenic tumor. Grossly, the mass was a well-circumscribed solid tumor, with yellow-tan cut surface and minute cystic spaces. Microscopically, the tumor showed well-defined epithelial nests with variable cystic changes embedded in an abundant fibrous stroma. The cells within the nests were reminiscent of benign urothelial cells in that they had oval, frequently grooved nuclei. The epithelial cells focally showed a gradual transition into the surrounding stromal cells with short spindled features. The urothelium-like cells were positive for pancytokeratin, WT-1, p63, CK7, uroplakin-III, and GATA-3 but were negative for CD34, CD10, CK20, c-KIT, DOG-1, PAX-8, and calretinin. Morphological and immunohistochemical features of the tumor were the same as an ovarian Brenner tumor, and so it was diagnosed as an extraovarian Brenner tumor.
  
  
  CONCLUSIONS
  Although the location of the tumor was very unusual, we could diagnose the tumor as an extraovarian Brenner tumor on the basis of the histologic and immunohistochemical findings. This is the first case of extraovarian Brenner tumor arising in the omentum near the stomach ever reported in the English literature.
authors.affiliation: Department of Pathology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
authors.forename: Chung Su
authors.initials: CS
authors.lastname: Hwang
authors.affiliation: Department of Pathology and Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea. cnlee@pusan.ac.kr.
authors.forename: Chang Hun
authors.initials: CH
authors.lastname: Lee
authors.affiliation: Department of Pathology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
authors.forename: So Jeong
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Department of Pathology and Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Young Geum
authors.initials: YG
authors.lastname: Kim
authors.affiliation: Department of Pathology and Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Ahrong
authors.initials: A
authors.lastname: Kim
authors.affiliation: Department of Pathology and Medical Research Institute, Pusan National University Hospital, Busan, Republic of Korea.
authors.forename: Do Youn
authors.initials: DY
authors.lastname: Park
authors.affiliation: Department of Pathology, Munhwa Hospital, Busan, Republic of Korea.
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Kang
authors.affiliation: Department of Pathology, Pusan National University Yangsan Hospital, Yangsan, Republic of Korea.
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Shin
mesh_terms: D000328:Adult; D001948:Brenner Tumor / Q000473:pathology* / Q000601:surgery; D005260:Female; D006801:Humans; D009852:Omentum / Q000473:pathology* / Q000601:surgery; D010051:Ovarian Neoplasms / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D017154:Stromal Cells / Q000473:pathology*
keywords: Brenner tumor; Extraovarian; Omentum