Figure 2

A 44-year-old woman with HR-HER + invasive ductal carcinoma. After 8 cycles of neoadjuvant chemotherapy (NAC, 4 cycles of anthracycline/cyclophosphamide followed by 4 cycles of taxane/trastuzumab), this patient received breast-conserving surgery. A 0.1-cm-sized ductal carcinoma in situ (DCIS) was found in the surgical specimen. a Pre-NAC magnetic resonance imaging (MRI) revealed an irregular enhancing mass in the left breast. b After completion of the NAC, the early post-contrast T1-weighted image showed no enhancing lesion. d In the late phase, a 0.7-cm-sized enhancing lesion was observed at the original tumour site (arrow). c,e are magnified subtraction images of each phase. Lesion-to-background signal enhancement ratios (SERs) were 1.1 in the early phase and 1.3 in the late phase. The presurgical core needle biopsy was diagnosed as atypical apocrine adenosis. According to our definitions of pathological complete response and the preliminary criteria, the MRI findings according to the criteria early size, early SER, and late SER were true negatives. Although the finding according to the criterion late size was a false positive, it may be suggestive of the residual DCIS.