HER2-positive luminal B breast cancer with axillary tumor deposits: no recurrence after multimodal therapy

What happened, in summary

This 58-year-old Tunisian woman presented with a palpable nodule in her left breast and no personal or family medical history. Examination found a firm, poorly defined 2 cm mass in the outer quadrants of the left breast with peau d’orange skin changes. No axillary nodes were palpable. Breast ultrasound and mammography were highly suspicious, classified ACR5, and core biopsy confirmed invasive breast carcinoma of no special type, Scarff-Bloom-Richardson grade III, luminal B, HER2-positive. The clinical stage was cT4bN0Mx, and further imaging did not show distant metastases. The locally advanced skin involvement made preoperative treatment important. She received 4 cycles of neoadjuvant epirubicin-cyclophosphamide followed by paclitaxel over 6 months, with hormone therapy and radiotherapy also included in her treatment course. Ultrasound and mammography after chemotherapy showed a radiologic complete response. She then underwent left mastectomy with ipsilateral axillary lymph node dissection. The mastectomy specimen showed a fibrous, whitish plaque with necrosis. Microscopy found residual viable tumor greater than 50%, indicating only partial pathologic response despite the radiologic findings. Vascular embolism was present, but margins were clear and there was no perineural invasion or Paget disease. Among 28 axillary nodules retrieved, 5 were metastatic lymph nodes, with extracapsular extension in 2. Another 14 nodules were tumor deposits without a lymph-node rim, capsule, or vascular/neural wall, a finding documented because tumor deposits may carry prognostic significance. The final stage was ypT1aN2aM0 after surgery. She continued hormone therapy and started trastuzumab. Follow-up found no complications, no detected recurrence, and good clinical condition.