ERBB2 and ductal breast carcinoma in situ: Although most of the synchronous carcinomas were ERBB2 non-amplified, one ERBB2 amplified case, S11 (with both IG papillary DCIS and mucinous carcinoma components), was shown by multiple shared CN gains and losses to be clonal with the atypical IDP lesion (Supplementary Fig. 10).