MED12 somatic mutations in fibroadenomas and phyllodes tumours of the breast

Salvatore Piscuoglio, Melissa Murray, Nicola Fusco, Caterina Marchiò, Florence L. Loo, Luciano G. Martelotto, Anne M. Schultheis, Muzaffar Akram, Britta Weigelt, Edi Brogi, Jorge S. Reis-Filho

Research output: Contribution to journalArticlepeer-review


Aims: Somatic mutations in exon 2 of the mediator complex subunit 12 (MED12) gene have been identified in 60% of breast fibroadenomas (FAs). The aim of this study was to define whether phyllodes tumours (PTs) would harbour MED12 somatic mutations in a way akin to FAs. Methods and results: A collection of 73 fibroepithelial tumours (including 26 FAs, 25 benign PTs, nine borderline PTs and 13 malignant PTs) from 64 patients was retrieved from the authors' institution. Sections from formalin-fixed paraffin-embedded (FFPE) blocks were microdissected to ensure an enrichment in neoplastic stromal elements of >70%. DNA samples extracted from tumour and matched normal tissues were subjected to Sanger sequencing of exon 2 of the MED12 gene. MED12 exon 2 somatic mutations, including 28 somatic single nucleotide variants and 19 insertions and deletions, were found in 65%, 88%, 78% and 8% of FAs, benign PTs, borderline PTs and malignant PTs, respectively. Malignant PTs harboured MED12 exon 2 somatic mutations significantly less frequently than FAs, benign and borderline PTs. Conclusions: Although MED12 exon 2 somatic mutations probably constitute the driver genetic event of most FAs, benign and borderline PTs, our results suggest that the majority of malignant PTs may be driven by other genetic/epigenetic alterations.

Original languageEnglish
Pages (from-to)719-729
Number of pages11
Issue number5
Publication statusPublished - Nov 1 2015


  • Breast
  • Fibroepithelial tumours
  • MED12
  • Sequencing
  • Somatic mutations

ASJC Scopus subject areas

  • Histology
  • Pathology and Forensic Medicine


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