TITLE:
A Case of Stage IV Breast Cancer Undergoing Surgery for Local Control after Developing a Breast Abscess during Chemotherapy
AUTHORS:
Katsutaka Watanabe
KEYWORDS:
Stage IV Breast Cancer, Triple-Negative, Breast Abscess, Palliative Mastectomy, Local Control
JOURNAL NAME:
Case Reports in Clinical Medicine,
Vol.14 No.11,
November
11,
2025
ABSTRACT: We report a case of a 47-year-old woman who presented with a left breast mass and bloody nipple discharge. Work-up revealed triple-negative breast cancer with liver metastases, staged T3N1M1 (stage IV). Systemic chemotherapy with bevacizumab and paclitaxel was initiated approximately 1 month after the first presentation. After four cycles, the primary tumor regressed (42% reduction in target lesion size per RECIST 1.1) and metastatic lesions remained stable; however, a breast abscess developed ~6 months after treatment initiation. Pus culture grew Staphylococcus aureus (methicillin-susceptible). Empirical piperacillin-tazobactam was initiated and later changed to cefazolin according to sensitivity testing. Despite 3 weeks of therapy and repeated drainage, infection persisted, causing severe pain, continuous purulent discharge, and a marked decline in quality of life (QOL). Therefore, total mastectomy with level I - II axillary dissection was performed through an elliptical incision encompassing the ulcerated skin, achieving negative margins and adequate drainage. Postoperative radiotherapy was given at 3 months post-surgery, and systemic chemotherapy was resumed at 4 months. The patient maintained progression-free survival for ~16 months after surgery but ultimately died from brain metastasis ~18 months postoperatively. This case illustrates that, in stage IV disease complicated by uncontrolled local infection, palliative surgery for local control can restore systemic-therapy feasibility and improve QOL.