title: Ovarian mucinous tumour arising in mature cystic teratoma and associated with pseudomyxoma peritonei: report of two cases and comparison with ovarian involvement by low-grade appendiceal mucinous tumour.
abstract: OBJECTIVE
  It is currently accepted that primary ovarian tumours rarely, if ever, give rise to mucinous ascites/pseudomyxoma peritonei (PMP) which most commonly results from the intra-abdominal spread of an appendiceal mucinous neoplasm. However, primary ovarian mucinous tumours of appendiceal type arising within mature cystic teratomas appear to represent an exception to this rule. In this report two further examples of this rare tumour are described, and the immunohistological phenotype including expression of MUC proteins is compared with secondary ovarian involvement by low-grade appendiceal mucinous neoplasm.
  
  
  METHODS
  Two cases of ovarian mucinous tumour associated with mature cystic teratoma and PMP are described. The tumours were examined immunohistochemically for expression of cytokeratin (CK)7, CK20, carcinoembryonic antigen (CEA), CDX-2, MUC2, MUC5AC and MUC6. The results were compared with four cases of ovarian neoplasia secondary to primary appendiceal low-grade mucinous tumour.
  
  
  RESULTS
  The ovarian mucinous tumours associated with mature cystic teratomas were morphologically similar to those secondary to appendiceal neoplasia. They comprised irregularly distributed glands and cysts lined by tall, mucin-rich epithelial cells exhibiting focal villoglandular architecture and low grade cytological atypia. The immunophenotype of the teratoma-associated tumours and those secondary to appendiceal neoplasia was identical: there was strong and diffuse expression of CK20, CEA, CDX-2, MUC2 and MUC5AC with no reactivity for the other antisera tested.
  
  
  CONCLUSIONS
  PMP associated with primary ovarian neoplasia is rare, and probably restricted to mucinous tumours arising in mature cystic teratomas. The immunohistological findings in this study further support the view that such tumours exhibit a lower gastrointestinal and, more specifically, appendiceal phenotype. Careful examination and sampling of the ovaries may be required to demonstrate the teratomatous component of these tumours.
authors: Departments of Histopathology and Gynaecological Oncology, King Edward Memorial Hospital, Perth, Western Australia. colin.stewart@health.wa.gov.au
authors: Colin J R
authors: CJ
authors: Stewart
authors: Tetsuya
authors: T
authors: Tsukamoto
authors: Bridget
authors: B
authors: Cooke
authors: Yee C
authors: YC
authors: Leung
authors: Ian G
authors: IG
authors: Hammond
mesh_terms: D002288:Adenocarcinoma, Mucinous / Q000473:pathology / Q000556:secondary*; D000328:Adult; D001063:Appendiceal Neoplasms / Q000473:pathology*; D000071616:CDX2 Transcription Factor; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D008875:Middle Aged; D055271:Mucin 5AC; D055262:Mucin-2; D009077:Mucins / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000473:pathology / Q000556:secondary*; D010534:Peritoneal Neoplasms / Q000473:pathology*; D011553:Pseudomyxoma Peritonei / Q000473:pathology*; D013724:Teratoma / Q000473:pathology*; D015534:Trans-Activators / Q000378:metabolism
chemical_list: D000071616:CDX2 Transcription Factor; D018398:Homeodomain Proteins; C524625:MUC2 protein, human; C524678:MUC5AC protein, human; D055271:Mucin 5AC; D055262:Mucin-2; D009077:Mucins; D015534:Trans-Activators