A 3-year-old girl is referred to the pediatric ophthalmology clinic for evaluation of bilateral leukocoria detected during school screening. Fundoscopy reveals multiple white retinal masses in both eyes, with the right eye showing larger lesions and vitreous haze, while the left eye has smaller, more peripheral lesions without vitreous involvement. B-scan ultrasonography and MRI confirm bilateral retinoblastoma with no evidence of optic nerve involvement or extraocular extension. Systemic staging (chest CT, bone marrow biopsy) is negative for metastases. The child's parents are unaffected, and there is no family history of retinoblastoma. What is the most appropriate initial treatment strategy for this child?

Explanation

## Bilateral Retinoblastoma: Paradigm Shift to Globe Salvage **Key Point:** Bilateral retinoblastoma requires a fundamentally different approach from unilateral disease. The goal is to preserve vision and globe function in at least one eye, if possible, while controlling tumor burden in both. Systemic neoadjuvant chemotherapy followed by focal consolidation is the modern standard of care. ## Treatment Algorithm for Bilateral Retinoblastoma ```mermaid flowchart TD A[Bilateral retinoblastoma confirmed]:::outcome --> B[Staging: assess extraocular extension]:::action B --> C{Metastatic disease?}:::decision C -->|Yes| D[Systemic chemotherapy + palliative care]:::urgent C -->|No| E[Neoadjuvant systemic chemotherapy]:::action E --> F[Assess response after 3-4 cycles]:::action F --> G{Tumor regression?}:::decision G -->|Good response| H[Focal consolidation therapy]:::action H --> I[Laser ablation/Cryotherapy/EBRT]:::action G -->|Poor response| J[Enucleation of worst eye]:::action I --> K[Salvage vision in at least one eye]:::outcome J --> L[Continue therapy in better eye]:::action ``` **High-Yield:** Systemic chemotherapy for bilateral retinoblastoma: - Achieves tumor regression in 70–80% of cases - Allows subsequent focal therapy (laser, cryotherapy) to consolidate response - Preserves vision and globe function in both eyes in ~50% of bilateral cases - Typical regimen: vincristine, etoposide, carboplatin (VEC) × 3–4 cycles - Response assessed by imaging after 3–4 cycles; focal therapy applied to residual disease ## Comparison: Unilateral vs. Bilateral Management | Feature | Unilateral (Advanced) | Bilateral | |---|---|---| | **Primary goal** | Cure, prevent metastasis | Preserve vision in ≥1 eye | | **First-line treatment** | Enucleation (if Group D–E) | Neoadjuvant chemotherapy | | **Role of chemotherapy** | Adjuvant (post-enucleation) | Neoadjuvant (pre-focal therapy) | | **Focal therapy** | N/A | Laser/cryo after chemo response | | **Bilateral enucleation** | Not applicable | Avoided unless both eyes unresponsive | **Clinical Pearl:** Bilateral retinoblastoma accounts for ~25% of all retinoblastoma cases and is associated with germline RB1 mutations in ~75% of cases. Genetic counseling and screening of parents and siblings is essential. The shift from bilateral enucleation to chemotherapy-based globe salvage has dramatically improved quality of life and functional outcomes in these children over the past two decades. **Mnemonic:** **SALVAGE** approach for bilateral RB: - **S**ystemic chemotherapy (neoadjuvant) - **A**ssess response by imaging - **L**aser/cryotherapy for consolidation - **V**ision preservation in ≥1 eye (goal) - **A**djuvant EBRT if needed - **G**ermline testing (RB1 mutation) - **E**nucleation only if both eyes fail to respond **Warning:** Bilateral enucleation in bilateral retinoblastoma is now considered overtreatment and is reserved only for cases with poor response to chemotherapy and focal therapy in both eyes. Modern protocols prioritize vision preservation. [cite:Murphree AL, Retinoblastoma. In: Yanoff & Duker Ophthalmology, 6e; International Society of Pediatric Oncology (SIOP) retinoblastoma guidelines]