title: Mutational analysis of MED12 exon 2 in a spectrum of fibroepithelial tumours of the breast: implications for pathogenesis and histogenesis.
abstract: OBJECTIVE
  Fibroadenomas (FAs) and phyllodes tumours (PTs) are fibroepithelial tumours. Mutations in MED12 exon 2 have been reported in FAs. This study investigated the MED12 mutations in a spectrum of fibroepithelial tumours.
  
  
  RESULTS
  Using direct sequencing, we analysed MED12 exon 2 mutations on 121 samples, including PTs and FAs and variants. We found MED12 mutations in 71.4% of PTs. No significant difference in the mutation frequency was observed between benign, borderline and malignant PTs, and a general lack of correlation existed between mutations and pathological factors associated with PT grading. The mutation patterns were similar between PTs and FAs, with codon 44 being involved most frequently. MED12 mutations were identified in 47.1, 52.6 and 50.0% of complex FAs, juvenile FAs and tubular adenomas (TAs), respectively, and the frequency and mutation patterns were similar between these FA variants and usual FAs.
  
  
  CONCLUSIONS
  The high frequency and similar patterns of MED12 mutations in FAs and various grades of PTs implies that the MED12 mutation is a common and early pathological event in these fibroepithelial tumours. The similar frequency and patterns of the MED12 mutation between FAs and variants suggests that FA variants are bona fide FAs, with identical pathogenesis involving MED12 mutations.
authors.affiliation: Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan.|Graduate Institute of Pathology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Huang-Chun
authors.initials: HC
authors.lastname: Lien
authors.affiliation: Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Chiun-Sheng
authors.initials: CS
authors.lastname: Huang
authors.affiliation: Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Ya-Wen
authors.initials: YW
authors.lastname: Yang
authors.affiliation: Department of Pathology, National Taiwan University Hospital, Taipei, Taiwan.|Graduate Institute of Pathology, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Yung-Ming
authors.initials: YM
authors.lastname: Jeng
mesh_terms: D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology*; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D005260:Female; D018226:Fibroadenoma / Q000235:genetics* / Q000473:pathology; D006801:Humans; D056892:Mediator Complex / Q000235:genetics*; D009154:Mutation; D003557:Phyllodes Tumor / Q000235:genetics* / Q000473:pathology
chemical_list: C460107:MED12 protein, human; D056892:Mediator Complex
keywords: MED12 mutation; fibroadenomas; phyllodes tumours