A 4-year-old boy presents with a rapidly enlarging, firm, non-tender mass in the superonasal quadrant of the left orbit that has doubled in size over three weeks. There is mild proptosis with downward and lateral displacement of the globe. CT shows an irregular enhancing soft tissue mass without bone destruction. The MOST likely diagnosis is:

• A Orbital rhabdomyosarcoma ✓
• B Optic nerve glioma
• C Dermoid cyst
• D Orbital pseudotumour

Explanation

Rhabdomyosarcoma is the most common primary malignant orbital tumour of childhood, typically presenting between 7 and 8 years of age as a rapidly progressive painless mass, most often superonasal. The explosive growth over weeks is characteristic. A dermoid cyst is present since birth and grows slowly, glioma arises along the optic nerve with early visual loss, and pseudotumour presents with pain and inflammation rather than a discrete mass.

Reference: Kanski's Clinical Ophthalmology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.