title: Claudin-18 overexpression in intestinal-type mucinous borderline tumour of the ovary.
abstract: OBJECTIVE
  Mucinous borderline tumours of the ovary are subclassified as intestinal-type (IMBT) and endocervical-like (EMBT), which differ in their clinicopathological features. In this study, we attempted to elucidate characteristics of the mucinous epithelium in each subtype.
  
  
  RESULTS
  The expression of claudin-18, a marker of gastric differentiation, MUCs, CDX2, CK7, CK20, oestrogen receptor (ER), progesterone receptor (PgR), CA-125 and vimentin in IMBTs (n = 54), EMBTs (n = 25) and serous borderline tumours (SBTs) (n = 22) were compared by immunohistochemistry. Claudin-18 positivity was identified in 98% of the IMBTs, whereas only 4% of the EMBTs were claudin-18-positive. Expression of intestinal markers such as CDX2 and MUC2 was relatively infrequent in IMBTs (48% and 33%, respectively). Müllerian-lineage markers such as ER, PgR and vimentin were expressed rarely in IMBTs, while most EMBTs and SBTs were positive for these markers. Hierarchial clustering revealed a close association between EMBTs and SBTs, while IMBTs were clearly separate.
  
  
  CONCLUSIONS
  Claudin-18 positivity is a specific phenotype that is characteristic of IMBTs. Frequent and diffuse expression of gastric markers, along with less frequent and usually focal expression of intestinal markers, suggests that IMBTs are essentially composed of gastrointestinal-type mucinous epithelium (gastric-type epithelium with a variable degree of intestinal differentiation).
authors.affiliation: Department of Pathology, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
authors.forename: Sultan Ahmad
authors.initials: SA
authors.lastname: Halimi
authors.forename: Daichi
authors.initials: D
authors.lastname: Maeda
authors.forename: Aya
authors.initials: A
authors.lastname: Shinozaki-Ushiku
authors.forename: Takahiro
authors.initials: T
authors.lastname: Koso
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsusaka
authors.forename: Mariko
authors.initials: M
authors.lastname: Tanaka
authors.forename: Takahide
authors.initials: T
authors.lastname: Arimoto
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Oda
authors.forename: Kei
authors.initials: K
authors.lastname: Kawana
authors.forename: Tetsu
authors.initials: T
authors.lastname: Yano
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Fujii
authors.forename: Masashi
authors.initials: M
authors.lastname: Fukayama
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D057167:Claudins / Q000096:biosynthesis*; D016000:Cluster Analysis; D018282:Cystadenocarcinoma, Mucinous / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D018291:Cystadenoma, Mucinous / Q000145:classification / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D010051:Ovarian Neoplasms / Q000145:classification / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; C486683:CLDN18 protein, human; D057167:Claudins
keywords: claudin-18; mucinous borderline tumour; ovary