A 18-month-old girl is brought to the emergency department with a 2-week history of progressive left eye proptosis, lid swelling, and periocular erythema. The mother reports that 6 months ago, the child had leukocoria in the left eye, but the family delayed seeking medical care. On examination, the left eye is markedly proptosed with restricted extraocular motility. Fundoscopy is obscured by media opacity. Contrast-enhanced CT of the orbits and brain shows a large intraocular mass with orbital extension and thickening of the optic nerve. There is no evidence of intracranial spread. Serum lactate dehydrogenase (LDH) is elevated at 450 U/L. What is the most appropriate next step in management?

Explanation

## Clinical Presentation: Extraocular Retinoblastoma This case represents **advanced retinoblastoma with orbital extension** — a serious prognostic scenario: **Key Point:** The critical findings are: - **Delayed diagnosis** (6 months from leukocoria to presentation) - **Orbital proptosis and restricted motility** — indicates orbital involvement - **Optic nerve thickening** on imaging — suggests extraocular extension - **Elevated LDH** — marker of tumor burden and systemic disease - **No intracranial spread** — important for prognosis ## Staging of Retinoblastoma: Intraocular vs. Extraocular | Stage | Definition | Prognosis | Treatment | |-------|-----------|-----------|----------| | **Intraocular (Groups A–E)** | Confined to eye | Favorable to intermediate | Chemotherapy ± focal therapy | | **Extraocular with optic nerve involvement** | Extends beyond lamina cribrosa | Poor | Enucleation + chemotherapy + radiotherapy | | **Extraocular with orbital involvement** | Extends into orbit | Very poor | Orbital exenteration ± chemotherapy ± radiotherapy | | **Metastatic disease** | CNS, bone, distant sites | Dismal | Multimodal chemotherapy ± radiotherapy | ## Management of Orbital Retinoblastoma ```mermaid flowchart TD A[Retinoblastoma with orbital extension]:::outcome --> B{Extent of orbital involvement?}:::decision B -->|Optic nerve only| C[Enucleation + systemic chemotherapy]:::action B -->|Orbital soft tissue| D[Orbital exenteration]:::action D --> E[Adjuvant chemotherapy]:::action E --> F[Consider EBRT if high risk]:::action C --> G[Assess for metastatic disease]:::decision G -->|No metastases| H[Systemic chemotherapy]:::action G -->|Metastases present| I[Intensive multimodal therapy]:::urgent F --> J[Long-term surveillance]:::outcome ``` **High-Yield:** Once retinoblastoma extends **beyond the lamina cribrosa into the orbit**, enucleation alone is insufficient — **orbital exenteration** (removal of the entire orbital contents including the eye, optic nerve, and surrounding soft tissue) becomes necessary to achieve adequate margins and prevent local recurrence. **Clinical Pearl:** Orbital involvement dramatically worsens prognosis (5-year survival ~50% vs. >95% for intraocular disease). The presence of optic nerve thickening on imaging is a strong indicator for exenteration rather than simple enucleation. ## Why Orbital Exenteration? 1. **Optic nerve thickening** indicates infiltration beyond the eye 2. **Orbital extension** requires wide surgical margins to prevent local recurrence 3. **Proptosis and motility restriction** suggest significant orbital involvement 4. **Enucleation alone is inadequate** and leads to high local recurrence rates 5. **Adjuvant chemotherapy + radiotherapy** address residual disease risk **Warning:** Do NOT confuse intraocular retinoblastoma (managed with chemotherapy + focal therapy) with extraocular/orbital disease (requires exenteration). The presence of orbital signs (proptosis, restricted motility, optic nerve changes) mandates exenteration. ## Post-Exenteration Management - **Histopathology review** of resected specimen for risk factors (optic nerve invasion, choroidal invasion, scleral invasion) - **Systemic chemotherapy** (typically 4–6 cycles) based on risk stratification - **External beam radiotherapy (EBRT)** if high-risk features present - **Orbital prosthesis** for rehabilitation - **Surveillance for metastatic disease** (chest imaging, bone scan, CSF examination if indicated) [cite:Murphree AL, Shields CL. Retinoblastoma. In: Yanoff M, Duker JS, eds. Ophthalmology. 5th ed. Ch 6.27]