Lobular Breast Cancer Spreading to an Eye Muscle

What happened, in summary

A 46-year-old woman had grade 2 pleomorphic lobular carcinoma of the right breast. The tumor was hormone receptor-positive and HER2-negative, with clinical stage cT3N3M0 and postoperative classification pT3N3Mx. She underwent mastectomy and axillary dissection, then received 4 cycles of epirubicin and cyclophosphamide, 12 weekly doses of paclitaxel, local radiation, and tamoxifen.

Bone metastases appeared 1 year later and were treated with letrozole and denosumab. Two years after that, she developed pain, double vision, eyelid swelling, and limited movement of the left eye. Imaging showed a 13 mm thickening of the left superior oblique muscle. Needle biopsy confirmed metastatic pleomorphic lobular breast cancer. The metastasis remained ER- and PR-positive and HER2- and E-cadherin-negative.

She received 3 monthly courses of liposomal doxorubicin followed by 30 Gy of stereotactic radiation in 5 daily fractions. Her pain and double vision resolved within a month, and imaging later showed complete local remission. Bone disease continued to progress initially, but weekly paclitaxel with denosumab produced stable disease at 6 months.