Table 3 International retinoblastoma classification

Stage 0: Patients treated conservatively (subject to presurgical ophthalmologic classifications)

Stage I: Eye enucleated, completely resected histologically

Stage II: Eye enucleated, microscopic residual tumor

Stage III: Regional extensiona

   a) Overt orbital disease

   b) Preauricular or cervical lymph node extension

Stage IV: Metastatic disease

   a) Hematogenous metastasis:

1. single lesion

2. multiple lesions

   b) CNS extension:

1. Prechiasmatic lesion

2. CNS mass

3. Leptomeningeal disease