What happened, in summary

A 76-year-old woman had no breast symptoms when a 0.9 cm right breast nodule was noticed incidentally on a chest CT performed for bronchiectasis. Mammography and ultrasound confirmed a complex solid and cystic mass measuring 1.1 × 0.9 × 1.1 cm.

Core biopsy showed invasive ductal carcinoma, grade 2, with mucinous features. The tumour was 95% estrogen-receptor positive and 70% progesterone-receptor positive, HER2 negative, with a Ki-67 index of 11–50%. The largest tumour focus in a biopsy core measured 0.5 cm.

She underwent needle localization, right partial mastectomy and sentinel lymph-node biopsy. The surgical specimen showed a 0.7 × 0.4 cm moderately differentiated invasive ductal carcinoma with mucinous features. Margins were clear, with the closest margin 0.3 cm away, and all 6 sampled lymph nodes were negative.

At the latest point described, she was receiving adjuvant radiation therapy to the breast. A course of anastrozole 1 mg daily for at least 5 years was planned after radiation.