ER-positive breast cancer: mastectomy after hormone therapy

What happened, in summary

A 56-year-old premenopausal Japanese woman was found to have a right breast mass and enlarged lymph nodes in both axillae during a medical examination in November 2018. Biopsy showed invasive ductal carcinoma with estrogen- and progesterone-receptor positivity and HER2 score 1+. PET imaging raised concern for lymph node disease, but biopsy of a left axillary node did not show malignancy, so the breast cancer was staged T2N0M0, Stage IIA. A major complication was severe neutropenia: her white blood cell count was 1.6 x 10^9/L and absolute neutrophil count was 0.3 x 10^9/L. Workup ruled out lymphoma, viral infection, bone marrow disease, lupus, Sjogren syndrome, and other secondary causes. Testing showed HNA-1 antibody positivity, supporting autoimmune neutropenia. While this was being evaluated, treatment began with anastrozole plus an LH-RH agonist. After 7 months, MRI showed the breast mass had decreased to 24 mm. Preoperative G-CSF did not improve the neutrophil count, so surgery proceeded with infection precautions and levofloxacin. She underwent total mastectomy with sentinel lymph node biopsy; the sentinel node was negative. Postoperatively, she had a fever without wound infection and was discharged after 6 days. Final pathology showed invasive ductal carcinoma with clear margins, ER positivity, PR negativity, HER2 score 0, and pT2 pN0 pMX disease. She continued anastrozole plus the LH-RH agonist and had no recurrence 3 years after surgery. The enlarged lymph nodes seen on imaging were therefore not treated as breast cancer spread, and the final node-negative pathology kept the cancer story consistent with early-stage disease complicated by autoimmune neutropenia.