Radiological foresight: a rare case of breast cancer metastases to the extraocular muscles.

To cite: Khan NA, Morlese J, Khan A. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/bcr-2015211264 DESCRIPTION A woman with a 1-year history of diplopia presented to the Ophthalmology Clinic in June 2014. She had a known history of infiltrating ductal carcinoma of the breast with metastasis to the bone and had undergone chemotherapy for this. On the day of her consultation, her visual acuity was 6/9 bilaterally and she was experiencing diplopia in extreme up and down gazes. She was referred for an MRI of the head and orbits, which revealed multiple metastatic deposits to the multiple extraocular muscles bilaterally (figures 1 and 2) as well as within the brain. Although rare, there are accounts of numerous malignancies with metastasis to the orbits, including breast, lung, genitourinary and gastrointestinal tumours. Of these, breast tumours have been reported as the most common malignancy to do so. However, bilateral metastasis to more than two extraocular muscles of this tumour, such as in this case, has been acknowledged as being very unusual. Patients with metastasis to the extraocular muscles usually present with symptoms of reduced vision, diplopia and pain in the region. Additionally, they may experience proptosis and ptosis. The diagnosis can only be confirmed histologically. In this case, the patient underwent a muscle biopsy from the left extraocular muscle, which confirmed the diagnosis of breast cancer metastasis. She was treated with whole brain radiotherapy and a follow-up MRI demonstrated she had had a partial response to this. She currently continues management under oncology.