Ewing's sarcoma as second malignancy following a short latency in unilateral retinoblastoma.

Second malignancies, mostly in the form of bone sarcomas, are known to occur in hereditary retinoblastomas, which usually present with bilateral disease. Only 2 cases of Ewing's sarcoma have been reported in the literature following sporadic unilateral retinoblastoma. A 5-year-old boy presented to our hospital with Ewing's sarcoma of the right humerus (proven by biopsy and immunohistochemistry) following successful treatment of retinoblastoma of the left eye with enucleation and chemotherapy 2 years previously. He was treated with 2 cycles of chemotherapy followed by radiation therapy. At 15 months follow-up, the tumor had reduced in size and the child had a good functional outcome. The cumulative risk of second malignancies in retinoblastoma survivors is 32%. Ninety-eight percent of second malignancies occur in patients with bilateral retinoblastoma. Germ line mutations have been considered in sporadic tumors occurring bilaterally and multifocal unilateral sporadic tumors. Bone and soft tissue sarcomas are the most common second malignancies. Radiation therapy increases the risk of developing a second malignancy in the irradiated field. Unilateral retinoblastomas, which comprise the majority of retinoblastomas, are not immune from the development of second malignancies. Close follow-up of all retinoblastomas--even in the early period--can improve the outcome by facilitating the early detection and aggressive treatment of second malignancies.