Supplementary Material for: Multidisciplinary treatment for locally advanced mucinous breast cancer

Background Due to its indolent biology and high estrogen receptor positivity of mucinous breast cancer, vast majority of locally advanced mucinous breast cancer (LABC) are treated with first line endocrine therapy.
Case presentation
A 50-year-old woman was referred to our hospital for the treatment of her huge breast tumor. Computed tomography showed an oval solid tumor, 17cm in size, and lymph node swelling both in the axilla and parasternum. Pathological study of the core needle biopsy specimen showed the tumor to be luminal mucinous carcinoma. After the failure of endocrine therapy aiming for tumor regression, the patient received sequential chemotherapy to get favorable local control, leading to marked tumor shrinkage. Axillar and parasternal lymph nodes, however, remained unchanged in size. The patient further underwent mastectomy and regional lymph node dissection including removal of the still enlarged parasternal lymph nodes followed by covering of the large skin defect with the lattissimus dorsi musculocutaneous (LDMC) flap using a spindle skin island, 15×8cm in size. Postoperative pathological study showed sparse cancer cell remnants with abundant mucus both in the primary tumor and the dissected lymph nodes. The patient has been well without any recurrences on endocrine therapy for 21 months.
Conclusion Breast oncologists should note that multidisciplinary treatment including preoperative chemotherapy and skin defect covering using LDMC flap can give favorable local control even to breast cancer patients with locally advanced mucinous breast cancer.