Stage 4 lobular breast cancer: bone therapy switch to denosumab

What happened, in summary

A 48-year-old woman with metastatic lobular breast cancer to bone developed a rare eye complication shortly after starting bone-support treatment. Her past history included total thyroidectomy and radioiodine treatment for papillary thyroid cancer in 2007. In December 2022, after a recent breast cancer diagnosis with bone metastasis, she was receiving goserelin (Zoladex) 10.8 mg by subcutaneous injection every 3 months and palbociclib 100 mg daily. About 48 hours after her first 4 mg intravenous zoledronate (Zometa) infusion on 12 December 2022, she developed left eye pain, upper-eyelid swelling, and decreased vision. She was first treated for presumed conjunctivitis, then received IV piperacillin/tazobactam in the emergency department for suspected orbital cellulitis before ophthalmology evaluation. Her left-eye vision had dropped to 20/80, with pain, restricted eye movement, swelling, redness, chemosis, and significant anterior-chamber inflammation. Ultrasound and CT showed thickened ocular coats, the T-sign suggestive of scleritis, periorbital swelling, lacrimal gland enlargement, fluid near the globe, and mild thickening of the lateral rectus muscle. Ophthalmology, oncology, and radiology found no evidence of orbital metastasis, choroidal metastasis, syphilis, tuberculosis, or leukocytosis. CRP and ESR were elevated. The picture fit non-infectious orbital inflammation with anterior and posterior scleritis, myositis, dacryoadenitis, and anterior uveitis, likely triggered by zoledronate. She was treated with hourly prednisolone drops, nightly dexamethasone ointment, cyclopentolate twice daily, and extended systemic dexamethasone. Inflammation resolved within 2.5 weeks, vision returned to 20/20 after about 3 weeks, zoledronate was stopped, and denosumab was substituted. No metastatic choroidal lesions were seen on complete eye examination, supporting the non-infectious treatment-related diagnosis.