Purpose: The authors report the clinicopathologic features of a recurrent retinoblastoma after radioactive iodine 125 (125l) plaque therapy.
Methods: The clinical and histopathologic findings of a 1-year-old boy with a recurrent retinoblastoma after 125l radioactive plaque application were reviewed. The patient's enucleated right eye was processed for routine histologic evaluation. Immunostains for glial fibrillary acid protein and S-100 protein were performed.
Results: Examination of the enucleated eye revealed a retinal tumor composed of two populations of cells. One population consisted of poorly differentiated cells, and the second population at the base of the tumor contained well-differentiated cells with numerous fleurettes. Immunohistochemical stains were positive for glial fibrillary acid protein and S-100 protein in the well-differentiated portion of the tumor.
Conclusion: This case illustrates a recurrent retinoblastoma that may have arisen from radioresistant well-differentiated cells after 125l plaque therapy.