Axillary accessory breast cancer with persistent leftsuperior vena cava: A case report and treatment controversy

INTRODUCTION: Axillary accessory breast cancer and persistent left superior vena cava (PLSVC) are rare clinically. Many controversial treatments for accessory breast cancer are worth discussing and learning. PRESENTATION OF THE CASE: A 48-year-old woman presented with biopsy histopathology confirmed. Right axillary mass biopsy pathology showed mucinous adenocarcinoma of accessory breast. She concerned that the axillary accessory breast cancer was more likely to metastasize and unsure about whether to remove the breast. She accepted extended right axillary accessory breast resection plus ipsilateral axillary lymph node dissection (ALND) and received chemotherapy. She was found to have a PLSVC before chemotherapy. DISCUSSION: Is there a need to remove the breast and perform ALND during axillary accessory breast cancer surgery? Is sentinel lymph node biopsy (SLNB) appropriate for axillary accessory breast cancer surgery? Can negative SLNB for axillary accessory breast cancer avoid ALND? Does accessory breast cancer without axillary lymph node metastasis require local radiotherapy? Does PLSVC impact the use of peripherally inserted central catheters (PICC) tubes during chemotherapy? Patients with accessory breast cancer without breast invasion should undergo local extended resection and ALND. SLNB for accessory breast cancer cannot instead of ALND. We recommend routine axillary radiotherapy after accessory breast cancer surgery. If it is determined that the tip of PICC is not in the coronary sinus of PLSVC, PLSVC does not affect chemotherapy. CONCLUSION: Many treatment strategies for accessory breast cancer require more evidence from evidence-based medicine. It is imperative to conduct multi-center accessory breast cancer research.