In DCIS, the significance of HER2 amplification remains unclear and might depend on various parameters.[19–22] Unlike in invasive carcinoma, the significance of the molecular phenotypes of DCIS remains unclear.[9] According to one study, the frequency of recurrence at 5 years was low in luminal A-type (ER/PgR+HER2-) DCIS, whereas it was high in HER2-type (ER and PgR-/HER2+) DCIS.[19] Our case corresponds to HER2-type DCIS. The gene discussed is ESR1; the disease is ductal breast carcinoma in situ.