Orbital Metastases

Haematogenous spread of a distant malignancy to the orbit, involving the bone, muscles, fat or lacrimal gland. About 2 to 3 percent of orbital tumours; the orbit is the commonest site of ocular metastasis after the uvea.

• Adults: breast carcinoma (most common, about 40 to 50 percent), lung, prostate, melanoma, renal cell carcinoma, gastrointestinal tumours, thyroid, and lymphoma and myeloma. The primary is unknown at presentation in about one quarter of cases.
• Children: neuroblastoma (periorbital ecchymosis and proptosis, "raccoon eyes", often bilateral), Ewing sarcoma, leukaemia, Wilms tumour, rhabdomyosarcoma.
• Pattern: infiltrative (scirrhous breast, causing enophthalmos and restriction), mass forming (renal, thyroid, lung), bone destructive (prostate, sclerotic; lung).

• Subacute onset (weeks to months) of proptosis or enophthalmos, pain, diplopia, ptosis, periorbital swelling, motility limitation (muscle involvement), infraorbital numbness, and a palpable mass.
• Enophthalmos with a tight orbit suggests scirrhous breast metastasis; rapid proptosis with ecchymosis in a child suggests neuroblastoma.
• Optic nerve compression: visual loss, relative afferent pupillary defect, disc swelling.
• Constitutional symptoms and a history of known malignancy, though often a late recurrence.

• MRI orbits and brain with contrast (muscle or bone lesions, diffuse infiltration, intracranial extension) and CT orbits (bone lysis or sclerosis); CT chest, abdomen and pelvis or whole body PET-CT for the primary and other sites.
• Tissue diagnosis: fine needle aspiration or incisional biopsy with immunohistochemistry (cytokeratin, oestrogen and progesterone receptors, PSA, TTF-1, thyroglobulin, PAX8, melanoma markers) to identify the primary.
• Blood tests: full count, calcium, alkaline phosphatase, tumour markers (CA 15-3, PSA, CEA), urine catecholamines in children.
• Differential: idiopathic orbital inflammation, thyroid eye disease, lymphoma, primary orbital tumour, orbital cellulitis.

• Palliative or disease modifying, based on the primary, the extent of disease and the patient's performance status.
• Radiotherapy to the orbit: 20 to 30 Gy in 5 to 10 fractions (commonly 30 Gy in 10 fractions) gives symptomatic relief and vision improvement in 60 to 80 percent; stereotactic radiotherapy for focal lesions.
• Systemic therapy per primary: hormonal therapy (tamoxifen 20 mg daily, aromatase inhibitors such as anastrozole 1 mg daily, with CDK4/6 inhibitors) in oestrogen receptor positive breast cancer, androgen deprivation (goserelin 10.8 mg every 12 weeks with abiraterone 1 g daily) for prostate, immunotherapy and targeted therapy for lung (osimertinib 80 mg daily for EGFR mutation), melanoma (nivolumab with ipilimumab) and renal cell carcinoma, chemotherapy for lymphoma and neuroblastoma.
• Corticosteroids: dexamethasone 4 to 8 mg daily for oedema and compression, with proton pump inhibitor.
• Surgery: limited to biopsy, debulking for pain or exposure, and exenteration in selected patients with a painful blind eye and good systemic prognosis.
• Ocular surface protection and pain control.
• Prognosis: median survival is short (about 1 year in lung and 2 to 3 years in breast), and the benefit is mainly palliation of pain and preservation of vision.