1. Case (II) Chemoresistant group

2. Case 6. F/41 Rt. breast cancer, 3 cycle NAC for 2 months (a) Indistinct margined, irregular shaped, hyperdense mass in Rt. UOQ with diffuse skin thickening axillary lymphadenopathies (b) No remarkable interval change of mass and axillary lymphadenopathies Newly developed another focal asymmetry in Rt. lower ab

3. (c) Indistinct margined, irregular shaped, hypoechoic mass with parallel orientation in Rt. UOQ (d) No remarkable interval change of main mass in Rt. UOQ And, multiple masses are newly developed in Rt. Breast. c d

4. * Confirmed as Invasive ductal carcinoma, HER-2 (+) * Residual tumor size is 5.5cm on final pathology after surgery (e) irregular margined and shaped, heterogeneously enhancing mass in Rt. UOQ on subtraction MRI (f) Mass is enlarged after NAC (5.4cm  6cm). ef

5. Case 7. F/48 Rt. breast cancer, 3 cycle NAC for 2 months (a)Indistinct margined, lobular shaped, hyperdense mass in Rt. upper mid with clustered microcalcifications (b) No remarkable interval change of mass and microcalcifications ab

6. (c) Indistinct and spiculated margined, oval shaped, hypoechoic mass in Rt. upper mid (d) Mass size is slightly decreased about 19% after NAC (2.1x1.5cm --> 1.7x1.1cm). c d

7. * Confirmed as Metaplastic carcinoma, ER weak (+) * Residual tumor size is 2.5cm on final pathology after surgery (e) irregular margined, round shaped, homogeneously enhancing mass in Rt. upper mid portion on subtraction MRI (f) Mass size is slightly decreased about 22% after NAC (2.2cm --> 1.7cm). ef

8. Case 8. F/53 Lt. breast cancer, 6 cycle NAC for 4 months (a) Spiculated margined, oval shaped, hyperdense mass in Lt. central portion Another mass in Lt. mid outer is fibroadenoma (b) Mass is slightly decreased in size after NAC. ab

9. (c) Spiculated margined, oval shaped, hypoechoic mass in Lt. central portion (d) mass size is slightly decreased about 7.7% after NAC (1.3x0.8cm  1.2x0.6cm) c d

10. * Confirmed as Invasive lobular carcinoma, ER (+) * Residual tumor size is 0.7cm on final pathology after surgery (e) spiculated margined, round shaped, homogeneously enhancing mass in Lt. central portion on sutraction MRI (f) Mass size is slightly decreased about 15 % after NAC (1.3cm --> 1.1cm). ef