MED12 and phyllodes tumor: Of 45 somatic mutations identified in fibroadenomas, the only gene that was recurrently mutated was MED12 22, suggesting that the MED12 exon 2 mutation is a major driving mutation underlying the pathogenesis of fibroadenoma; however, the status of the mutations in phyllodes tumors, related to fibroadenomas, remains to be clarified.