title: Collision tumors of the ovary associated with teratoma: clues to the correct preoperative diagnosis.
abstract: OBJECTIVE
  Collision tumors represent a coexistence of two adjacent but histologically distinct tumors without histologic admixture in an organ. The purpose of this study was to describe the imaging findings of collision tumors of the ovary associated with teratoma and to look for clues that might lead to the correct preoperative diagnosis.
  
  
  METHODS
  Seven pathologically proven cases of collision tumor of the ovary associated with teratoma were retrospectively reviewed. Ovarian teratomas were coexistent with mucinous cystadenoma (n = 4), borderline mucinous tumor (n = 1), mucinous cystadenocarcinoma (n = 1), and dysgerminoma (n = 1). US (n = 5), CT (n = 3), and/or MRI (n = 4) findings were evaluated.
  
  
  RESULTS
  In addition to the typical findings of teratoma, the mass contained a multiloculated cystic portion filled with nonfatty fluid, suggesting the coexistent epithelial tumor in five cases. In one case, the mass contained a large solid component, suggesting the possibility of collision tumor. In the remaining one case, coexistent small mucinous cystadenoma could not be identified.
  
  
  CONCLUSIONS
  Preoperative imaging for ovarian teratoma revealed a collision tumor in six of seven cases. The possibility of a collision tumor should be considered when an ovarian teratoma has imaging findings that cannot be explained solely by an ovarian teratoma.
authors.affiliation: Department of Radiology and Institute of Radiation Medicine, Seoul National University College of Medicine, Korea.
authors.forename: S H
authors.initials: SH
authors.lastname: Kim
authors.forename: Y J
authors.initials: YJ
authors.lastname: Kim
authors.forename: B K
authors.initials: BK
authors.lastname: Park
authors.forename: J Y
authors.initials: JY
authors.lastname: Cho
authors.forename: B H
authors.initials: BH
authors.lastname: Kim
authors.forename: J Y
authors.initials: JY
authors.lastname: Byun
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000328:Adult; D003287:Contrast Media; D018282:Cystadenocarcinoma, Mucinous / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D018291:Cystadenoma, Mucinous / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D003937:Diagnosis, Differential; D004407:Dysgerminoma / Q000175:diagnosis / Q000000981:diagnostic imaging / Q000473:pathology; D005122:Exudates and Transudates; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000175:diagnosis; D009378:Neoplasms, Multiple Primary / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D010051:Ovarian Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D012189:Retrospective Studies; D013724:Teratoma / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA