RETINOBLASTOMA RECURRENCE AFTER IODINE-125 PLAQUE APPLICATION

Purpose: The authors report the clinicopathologic features of a recurr ent retinoblastoma after radioactive iodine 125 (I-125) plaque therapy . Methods: The clinical and histopathologic findings of a 1-year-old b oy with a recurrent retinoblastoma after I-125 radioactive plaque appl ication were reviewed. The patient's enucleated right eye was processe d for routine histologic evaluation. Immunostains for glial fibrillary acid protein and S-100 protein were performed. Results: Examination o f the enucleated eye revealed a retinal tumor composed of two populati ons of cells. One population consisted of poorly differentiated cells, and the second population at the base of the tumor contained well-dif ferentiated 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 il lustrates a recurrent retinoblastoma that may have arisen from radiore sistant well-differentiated cells after I-125 plaque therapy.