## International Classification of Retinoblastoma (ICRB) and Prognosis **Key Point:** Group E retinoblastoma has the worst prognosis for globe salvage and represents advanced intraocular disease with secondary glaucoma, rubeosis iridis, or phthisical changes. Enucleation is typically the only option. ### ICRB Classification System | Group | Features | Globe Salvage Rate | Treatment | | --- | --- | --- | --- | | **A** | Small, confined to retina, no vitreous seeding | >95% | Chemotherapy, focal therapy | | **B** | Minimal vitreous seeding, small tumor | >90% | Chemotherapy, focal therapy | | **C** | Moderate vitreous seeding, medium tumor | 70–80% | Chemotherapy, focal therapy ± external beam | | **D** | Significant vitreous seeding, large tumor | 50–60% | Chemotherapy, external beam, focal therapy | | **E** | Phthisis, rubeosis, hyphema, neovascular glaucoma | <5% | **Enucleation** (primary) | **High-Yield:** Group E is essentially **end-stage intraocular disease**. The presence of iris neovascularization (rubeosis iridis) indicates extensive tumor burden and secondary glaucoma that cannot be reversed. ### Why Group E Has Worst Prognosis 1. **Extensive tumor burden:** Tumor has infiltrated beyond salvageable limits 2. **Secondary glaucoma:** Neovascular glaucoma from tumor-derived VEGF is refractory to medical management 3. **Phthisical changes:** Shrinkage and fibrosis of the eye indicate end-stage disease 4. **High metastatic risk:** Advanced intraocular disease correlates with extraocular extension and systemic spread **Clinical Pearl:** Any eye with rubeosis iridis (iris neovascularization) in the context of retinoblastoma should be considered for primary enucleation, as salvage attempts are futile and delay systemic treatment. **Warning:** Do not confuse Group E with Group D. Group D has significant vitreous seeding but retains some salvage potential with aggressive multimodal therapy. Group E is irreversible. 
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