Late-diagnosis retinoblastoma with germline mosaicism in an 8-year-old

We describe bilateral retinoblastoma in an 8-year-old girl presenting with macular tumor in one eye and a small peripheral tumor in the other but no detected RB1 gene mutation. Despite chemotherapy, multiple focal laser, cryotherapy, and periocular chemotherapy, tumor activity persisted and enucleation was performed. Two RB1 mutations were found in the tumor; one RB1 mutation was present in 10% of blood cells, identifying mosaicsm.