CT neck with contrast in a patient with progressive proptosis and ophthalmoplegia shows a well-encapsulated extraconal orbital mass that is smoothly oval, heterogeneous with fat density and calcification ('teeth'), and does not enhance. This is located superior and temporal. The likely diagnosis and characteristic CT finding are:

• A Cavernous haemangioma — well-encapsulated, progressive filling on dynamic CT
• B Schwannoma — fusiform, isodense with moderate enhancement
• C Rhabdomyosarcoma — infiltrative, heterogeneous with bony destruction
• D Mature teratoma (dermoid cyst) with fat, calcium, and tooth-like calcifications within the orbit ✓

Explanation

Orbital dermoid/mature teratoma on CT shows a well-defined encapsulated mass containing fat (−50 to −100 HU), calcification, and occasionally tooth-like structures derived from ectoderm — all characteristic of a dermoid. Located typically at the superolateral orbital margin near the frontozygomatic suture. Cavernous haemangioma is the most common adult orbital tumour and shows progressive centripetal filling on dynamic CT. Schwannoma is isodense with enhancement. Rhabdomyosarcoma is the most common orbital malignancy in children and is infiltrative.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.