HISTOPATHOLOGIC STUDY OF EYES AFTER IODINE I-125 EPISCLERAL PLAQUE IRRADIATION FOR UVEAL MELANOMA

Objectives: To describe the histopathologic findings attributable to i rradiation in eyes with uveal malignant melanoma treated with iodine I 125 brachytherapy and to compare these findings with those reviewed i n a previous study that compared histopathologic findings in eyes enuc leated after pro ton beam teletherapy with those seen in eyes in a non irradiated control group. Methods: The slides from 22 eyes with uveal melanoma that had undergone enucleation after the administration of I- 125 brachytherapy were studied. The histopathologic features of the tu mor and the retina were graded. Results were compared with findings fr om a previously reported group of 47 proton beam-treated eyes and its control group. Results: Patient age, time between irradiation and enuc le ation, and ciliary body involvement were similar for the I-125 brac hytherapy-treated group and the proton beam-treated group and its cont rol group. This allows comparison of the histopathologic findings. Com paring the I-125 brachytherapy-and proton beam-treated groups, most hi stopathologic features were similar with nominally statistically signi ficant differences only for cell type, number of mitotic figures, and fibrous metaplasia of the retinal pigment epithelium adjacent to the t umor. Conclusions: Irradiation of uveal melanoma induces changes in th e tumor and in the surrounding retina. Brachytherapy and charged parti cle therapy are the 2 principal methods of irradiation. This study dem onstrates that similar changes are produced by I-125 plaque irradiatio n and proton beam irradiation.