Breast cancer dermal lymphatic invasion recurrence and contralateral axillary lymph nodes metastasis after complete response to neoadjuvant therapy: A case report.

Introduction And Importance: Non-luminal type breast cancer patients with pathological complete response (pCR) by neoadjuvant chemotherapy (NAC) usually have a good prognosis, but occasionally recurrence occurs.

Case Presentation: A 61-year-old woman was diagnosed with breast cancer T2N2aM0 stage IIIA and its intrinsic type was non-luminal type. After NAC, the patient achieved pCR and underwent breast-conserving surgery and axillary lymph node dissection (ALND). Radiotherapy and trastuzumab of one-year duration was added. However, six years and two months later, local recurrence and contralateral axillary lymph node (CLALN) metastasis were identified. After resection, anti-human epidermal growth factor receptor 2 (HER-2) therapy was done, however, six months after operation, purpura was observed on the right chest and tended to increase. One and a half years after re-operation, dermal lymphatic invasion (DLI) recurrence without clinical inflammatory signs was diagnosed. A skin resection was performed >1.5 cm away from the purpura, and the surgical margins were negative but four months later, a recurrence re-emerged.

Clinical Discussion: CLALN metastasis is considered distant metastasis based on the current TNM classification. However, as previous ALND or radiotherapy can change lymphatic flow, the resulting CLALN may not be distant metastasis. DLI recurrence without clinical inflammatory signs is likely to be resistant to anti-HER2 even in non-luminal type, and even a 2-cm margin for skin surgical lines may result in positive margins.

Conclusion: There are cases where CLALN after ALND should also be considered possible metastasis. In DLI recurrence, the skin excision margin line should be set very generously.