RT Journal Article SR Electronic T1 Recurrent MED12 exon 2 mutations in benign breast fibroepithelial lesions in adolescents and young adults JF Journal of Clinical Pathology JO J Clin Pathol FD BMJ Publishing Group Ltd and Association of Clinical Pathologists SP 258 OP 262 DO 10.1136/jclinpath-2018-205570 VO 72 IS 3 A1 Pareja, Fresia A1 Da Cruz Paula, Arnaud A1 Murray, Melissa P A1 Hoang, Timothy A1 Gularte-Mérida, Rodrigo A1 Brown, David A1 da Silva, Edaise M A1 Sebastiao, Ana Paula Martins A1 Giri, Dilip D A1 Weigelt, Britta A1 Reis-Filho, Jorge S A1 Brogi, Edi YR 2019 UL http://jcp.bmj.com/content/72/3/258.abstract AB Aims Most benign breast fibroepithelial lesions (FEL) in adults harbour recurrent somatic MED12 exon 2 mutations and rare TERT promoter hotspot mutations. We sought to determine the frequency of MED12 exon 2 and TERT promoter hotspot mutations in fibroadenomas (FA) and benign phyllodes tumours (BePT) in adolescents and young adults.Methods DNA from 21 consecutive FAs and eight consecutive BePTs in adolescents and young adults was subjected to Sanger sequencing of the exon 2 of MED12 and the TERT promoter hotspot locus.Results We identified MED12 exon 2 mutations in 62% and 88% of FAs and BePTs, respectively, and no TERT promoter hotspot mutations. The majority of the MED12 exon 2 mutations identified were in-frame deletions (60%).Conclusions As in adults, benign FELs in juvenile patients harbour recurrent MED12 exon 2 mutations.