A 55-year-old woman presents with a unilateral slowly progressive proptosis for 2 years. CT orbit shows a well-defined, homogeneously enhancing intraconal mass with no bony erosion, moulding around the optic nerve. The most likely diagnosis is:

• A Orbital pseudotumour (idiopathic orbital inflammation)
• B Orbital lymphoma
• C Cavernous haemangioma (venous malformation) of the orbit ✓
• D Metastatic orbital disease

Explanation

Cavernous haemangioma (now classified as venous malformation) is the most common primary benign intraconal orbital tumour in adults. It presents as a slowly progressive proptosis with a well-circumscribed, homogeneously enhancing round or oval intraconal mass that does not erode bone. Orbital pseudotumour is painful, rapidly progressive, and may respond to steroids; lymphoma shows a moulded 'cast' along orbital walls on CT; metastases usually cause irregular destructive changes.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.