Retinoblastoma presenting as leukocoria in a 2-year-old is confirmed by B-scan showing a highly reflective mass with calcification. The International Classification of Retinoblastoma (ICRB) Group E tumor is defined as:

• A Tumor ≤ 3 mm, confined to retina away from fovea and disc
• B Tumor with subretinal seeding within 3 mm of the lesion
• C Extensive tumor occupying > 50% of globe volume, or with neovascular glaucoma, opaque media, or involvement of the anterior segment ✓
• D Diffuse vitreous seeding without a distinct tumor mass

Explanation

The ICRB classifies retinoblastoma from Group A (very low risk) to Group E (very high risk of enucleation). Group E is the most advanced intraocular stage, defined as extensive tumor (> 50% globe volume), neovascular glaucoma from extensive involvement, opaque media due to VH or tumor, anterior segment involvement (iris seeding, hyphema), or phthisis/prephthisis. Such eyes almost always require primary enucleation as chemotherapy has poor success rates. Group A is the smallest tumor with best globe salvage prognosis.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.