title: Frequent MED12 mutations in phyllodes tumours of the breast.
abstract: BACKGROUND
  Phyllodes tumours are rare fibroepithelial tumours of the breast, that include benign, borderline, and malignant lesions. Although the molecular basis of phyllodes tumours largely remains unknown, a recent exome study identified MED12 mutations as a sole recurrent genetic alteration in fibroadenoma, a common benign fibroepithelial tumour that shares some histological features with the phyllodes tumour.
  
  
  METHODS
  Forty-six phyllodes tumours and 58 fibroadenomas of the breast were analysed for MED12 mutations by using Sanger sequencing.
  
  
  RESULTS
  MED12 mutations were identified in 37 out of the 46 phyllodes tumours (80%). The prevalence of MED12 mutations was similar among benign (15/18, 83%), borderline (12/15, 80%), and malignant tumours (10/13, 77%). MED12 mutations were also identified in 36 of the 58 fibroadenomas (62%). The mutations were frequent among intracanalicular-type (24/32, 75%) and complex-type lesions (4/6, 67%), but were significantly less common among the pericanalicular-type lesions (8/20, 40%). A microdissection-based analysis showed that MED12 mutations were confined to the stromal components in both phyllodes tumours and fibroadenomas.
  
  
  CONCLUSIONS
  MED12 mutations were frequent among the phyllodes tumours of the breast, regardless of the tumour grade. Phyllodes tumours and fibroadenomas share, at least in part, a common genetic background.
authors.affiliation: Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo 104-0045, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: 1] Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo 104-0045, Japan [2] Division of Molecular Pathology, National Cancer Center Research Institute, Tokyo 104-0045, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Sekine
authors.affiliation: Division of Molecular Pathology, National Cancer Center Research Institute, Tokyo 104-0045, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Ogawa
authors.affiliation: Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo 104-0045, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.affiliation: Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo 104-0045, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Maeshima
authors.affiliation: Division of Molecular Pathology, National Cancer Center Research Institute, Tokyo 104-0045, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Kanai
authors.affiliation: Breast Surgery Division, National Cancer Center Hospital, Tokyo 104-0045, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Kinoshita
authors.affiliation: Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo 104-0045, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Ochiai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics*; D005260:Female; D018226:Fibroadenoma / Q000235:genetics; D006801:Humans; D056892:Mediator Complex / Q000235:genetics*; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D003557:Phyllodes Tumor / Q000235:genetics*; D055815:Young Adult
chemical_list: C460107:MED12 protein, human; D056892:Mediator Complex
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