Background: The most frequent second malignant neoplasm after retinoblastoma is osteosarcoma, which may be associated with radiation therapy or arise de novo in patients with bilateral retinoblastoma.
Methods: Clinical, pathologic, and diagnostic imaging findings in two patients with Ewing sarcoma (ES) and one with peripheral neuroepithelioma (PN) are presented.
Results: Second malignant neoplasms located in the extremities or pelvis were seen 12-18 years after initial diagnosis of unilateral (two patients) or bilateral (one patient) retinoblastoma. The patients with unilateral retinoblastoma were treated by enucleation only; the other received ocular radiation therapy and chemotherapy. To the knowledge of the authors, this is the first documentation of round blue cell tumor after unilateral retinoblastoma.
Conclusions: ES and PN should be included in the differential diagnosis of malignant neoplasms occurring after treatment of unilateral or bilateral retinoblastoma.