Retinoblastoma in dizygotic twins born as extremely low birth weight infants

A case of bilateral retinoblastoma affecting both of a pair of dizygotic twins was reported. To our knowledge, there has been only one previous report of dizygotic twins, both affected, with this disease. The present twins had no family history of retinoblastoma. They were born prematurely as extremely low birth weight infants after 26 weeks and 4 days of gestation, and 3 of the 4 tumors were detected at 33 weeks after conception. Using LINAC external radiation therapy followed by xenon photocoagulation when necessary, the tumors were successfully treated. These cases show that retinoblastoma can develop in the pre-term period, indicating that the second mutation involved in tumorigenesis can occur in the fetus.