Necrosis of a Metastatic Axillary Lymph Node in Breast Cancer Possibly Induced by Fine-Needle Aspiration Cytology: A...

Axillary lymph node metastasis is a major prognostic factor for breast cancer. In rare cases, metastatic lesions may undergo necrosis.

A 69-year-old woman with a history of rheumatoid arthritis and ovarian tumor surgery was diagnosed with right-sided breast cancer (cT1N1M0) following abnormal screening mammography. Core needle biopsy revealed invasive ductal carcinoma (estrogen receptor: >95%, progesterone receptor: <1%, human epidermal growth factor receptor 2: 2+ [fluorescence in situ hybridization-negative], MIB-1: 18%). Fine-needle aspiration (FNA) cytology of an enlarged axillary lymph node confirmed metastasis. Mastectomy and axillary dissection were performed approximately 3 months after the FNA procedure without preoperative treatment, suggesting a temporal relationship between aspiration and subsequent necrosis. Histopathological analysis revealed no viable cancer cells in the lymph nodes but uniform eosinophilic necrosis with partial epithelial-like structures in one node. Immunohistochemistry showed positivity for epithelial membrane antigen, AE1/AE3, estrogen receptor, and GATA3, and histiocytes surrounding the necrotic area were positive for cluster of differentiation 68 and 163. These findings suggested that the metastatic carcinoma had undergone necrosis, likely triggered by FNA. The Oncotype DX score was 33; however, the patient chose endocrine therapy alone. No recurrence has been observed at the time of writing, 18 months after surgery.

This case highlights a rare instance of necrosis in a metastatic lymph node, possibly induced by FNA. Immunohistochemistry is essential to confirm the diagnosis and avoid misinterpretation as a granulomatous or infectious process.