## International Classification of Retinoblastoma (ICRB) **Key Point:** Group E retinoblastoma carries the worst prognosis for globe salvage and typically requires enucleation. ### ICRB Stratification (Groups A–E) The classification system predicts likelihood of preserving vision and the globe: | Group | Features | Globe Salvage Rate | |-------|----------|-------------------| | **A** | Small intraocular tumor, favorable location, no vitreous seeding | ~95% | | **B** | Larger tumor or vitreous seeding, but no total retinal detachment | ~90% | | **C** | Localized vitreous seeding or total retinal detachment in one quadrant | ~50% | | **D** | Diffuse vitreous seeding or total retinal detachment | ~10% | | **E** | Massive tumor, phthisis bulbi, neovascular glaucoma, anterior chamber involvement, or extensive extraocular disease | <5% (enucleation) | **High-Yield:** Group E is defined by **massive intraocular disease with poor prognosis** — these eyes are typically enucleated rather than treated with globe-salvaging therapy. ### Clinical Implications - **Groups A–D**: Candidates for chemotherapy, external beam radiotherapy, brachytherapy, or cryotherapy - **Group E**: Enucleation is standard; systemic chemotherapy may be given to reduce metastatic risk **Clinical Pearl:** The presence of **neovascular glaucoma** or **anterior chamber involvement** automatically places a tumor in Group E, as these features indicate advanced disease incompatible with globe salvage. 
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