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case_images: Images of mammary magnetic resonance imaging (MRI) in different phases. (A) The baseline mammary magnetic resonance imaging (MRI) in November 2017. (B) Mammary MRI after five cycles of TCbH regimen in February 2018. (C) Mammary MRI after four cycles of ECH regimen in May 2018. (D) Mammary MRI after two cycles of nab-paclitaxel plus trastuzumab regimen in July 2018. (E, F) Mammary MRI after four cycles of nab-paclitaxel plus trastuzumab regimen in August 2018. (G) Mammary MRI after two cycles of pyrotinib plus capecitabin regimen in October 2018. (H) Mammary MRI after four cycles of pyrotinib plus capecitabin regimen in November 2018. (I) Mammary MRI after six cycles of pyrotinib plus capecitabin regimen in December 2018.
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case_images: In October 2017, she was admitted to our hospital and received mammary magnetic resonance imaging (MRI) ( Figure 1A ), which showed a 91 mm x 55 mm x 87 mm mass with ill-defined margins and a heterogeneous internal enhancement in the left breast; breast imaging reporting and data system (BI-RADS) category was identified as 5. After five cycles (November 6, 2017-January 30, 2018), reexamination of mammary MRI ( Figure 1B ) showed the size of the mass shrank from 91 mm x 55 mm x 87 mm to 84 mm x 48 mm x 72 mm. According to the evaluation criteria of Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1, we judged the therapeutic effect as stable disease (SD). After four cycles, re-examined mammary MRI ( Figure 1C ) showed that the tumor shrank from 84 mm x 48 mm x 72 mm to 66 mm x 29 mm x 56 mm. The patient got PR after the first two cycles ( Figure 1D ), but two cycles later, the efficacy deteriorated to progressive disease (PD) ( Figure 1E ). After six cycles (August 28, 2018-December 29, 2018), the patient got PR ( Figures 1F-I ), and the surface of the breast almost completely healed ( Figures 3D-F ).
case_images: Pathology images and immunotherapy staining images of this patient. (A) Pathology images of core needle biopsy in October 2017. (B) ER immunotherapy staining image of core needle biopsy in October 2017. (C) PR immunotherapy staining image of core needle biopsy in October 2017. (D) HER2 immunotherapy staining image of core needle biopsy in October 2017. (E) Ki-67 immunotherapy staining image of core needle biopsy in October 2017. (F) Pathology images of mastectomy in January 2019. (G) ER immunotherapy staining image of mastectomy in January 2019. (H) PR immunotherapy staining image of mastectomy in January 2019. (I) HER2 immunotherapy staining image of mastectomy in January 2019. (J) Ki-67 immunotherapy staining image of mastectomy in January 2019.
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case_images: Subsequently, core needle biopsy was performed on October 28, 2017, and invasive ductal carcinoma was pathologically diagnosed, histological grade 2, with estrogen receptor (ER) negative and progesterone receptor (PR) negative, overexpression of HER-2 (+++), and high proliferation index Ki-67 (70%) ( Figures 2A-E ). Left breast cancer mastectomy and local rotation skin flap grafting were performed on the patient in January 16, 2019, and postoperative pathology report showed an invasive ductal carcinoma with changes in Miller-Payne Grade 4 ( Figure 2F ), with a tumor size of 1.0 cm x 0.8 cm x 0.8 cm and lymph nodes negative (0/14). Immunohistochemistry indicated ER (-), PR (-), C-erbb-2 (+++), and ki-67 (70%+) ( Figures 2G-J ).
case_images: Appearances of breast or chest wall in different phases. (A) The appearance of breast before ECH regimen in March 2018. (B) The appearance of breast after two cycles of ECH regimen in April 2018. (C) The appearance of breast after four cycles of ECH regimen in May 2018. (D) The appearance of breast before pyrotinib plus capecitabin regimen in August 2018. (E) The appearance of breast after two cycles of pyrotinib plus capecitabin regimen in October 2018. (F) The appearance of breast after six cycles of pyrotinib plus capecitabin regimen in October 2018. (G) The appearance of left chest wall 5 months after surgery in June 2019. (H) The appearance of left chest wall 26 months after surgery in March 2021.
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case_images: There was no significant change in the appearance of the breast ( Figures 3A-C ). After six cycles (August 28, 2018-December 29, 2018), the patient got PR ( Figures 1F-I ), and the surface of the breast almost completely healed ( Figures 3D-F ). By the time of contribution, the second (June 2019) and last regular follow-ups (March 2021) showed no signs of metastasis or recurrence ( Figures 3G, H ).
case_images: Next-generation sequencing (NGS) showed L755S mutation in exon19 of ERBB2 gene.
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case_images: L755S ( Figure 4 ) and K907R mutation. L755S mutation indicated resistance to trastuzumab and lapatinib and may be sensitive to neratinib, an irreversible pan-HER TKI.