RESUMEN
To report a case of a child with the hereditary form of unilateral retinoblastoma [RB], who developed Ewing's sarcoma of the right fibula 3 years after the enucleation of the right eye. The child was diagnosed as a case of RB of the right eye at the age of 9 months. He was fully investigated and found to have locally advanced RB with bone marrow involvement [Reese-Ellsworth stage IVA]. Enucleation was recommended to the family, but they refused. The patient received chemotherapy and diode laser thermotherapy in Kuwait and the UK. He had a local relapse after 11 months and subsequently underwent enucleation of the right eye. After 3 years, he was investigated for a small swelling in his right lower leg. After extensive investigations, it was reported as Ewing's sarcoma. He was treated with chemotherapy, surgery [complete excision of the fibula] and high-dose chemotherapy followed by autologous stem cell transplantation. The child is now nearly 2 years after completing the treatment and is disease free. This case confirms the increased risk of a second malignant neoplasm [SMN] in children with hereditary RB. These children need a very close follow-up for the early diagnosis of SMNs or even subsequent malignancies