What happened, in summary

A 47-year-old woman returned for diagnostic breast imaging 7 months after a routine screening mammogram had been negative. She had first felt a right breast lump 1 month after the screening examination, and it had enlarged over the next 6 months.

Ultrasound showed a complex solid and cystic mass measuring 4.9 × 3.1 × 4.9 cm. A second solid lesion measuring 0.8 × 0.5 × 0.6 cm sat 1.5 cm away and was considered a possible satellite lesion.

Core biopsy of the dominant mass found infiltrating mammary carcinoma with focal features suggestive of metaplastic carcinoma, including osteoclast giant cells and focal squamous metaplasia. Ductal carcinoma in situ was also present. The invasive tumour was 95% estrogen-receptor positive and 95% progesterone-receptor positive, HER2 negative, with a Ki-67 index of 11–50%.

At the latest point described, she was awaiting biopsy of the smaller lesion to help determine whether breast-conserving surgery would be feasible. Neoadjuvant chemotherapy was planned before definitive surgery. Her treatment course was still at the planning stage, with chemotherapy expected to precede definitive surgery.