A 45-year-old woman presents with acute onset of painful proptosis, periorbital edema, and chemosis in the left eye for 5 days. There is no history of trauma or thyroid disease. CT shows diffuse infiltration of the orbital fat and extraocular muscles with irregular margins. The most likely diagnosis is:

• A Orbital lymphangioma
• B Orbital varix
• C Orbital metastasis
• D Idiopathic orbital inflammation (orbital pseudotumor) ✓

Explanation

Idiopathic orbital inflammation (orbital pseudotumor) classically presents with acute painful proptosis, periorbital edema, and chemosis in a middle-aged adult. CT typically shows diffuse infiltration of orbital fat, extraocular muscle enlargement with tendinous involvement, and irregular margins. It is a diagnosis of exclusion and responds dramatically to corticosteroids. Orbital varix causes positional proptosis, lymphangioma presents in children, and orbital metastasis usually has a known primary.

Reference: Rootman's Diseases of the Orbit, 3rd ed.

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Written and medically reviewed by the StethoPrep medical team.