Histopathological characteristics of secondary enucleation after iodide-125 plaque radiotherapy in Chinese patients with uveal melanoma.

Abstract

To explore the histopathological characteristics in eyes with uveal melanoma (UM) that had secondary enucleation after iodine-125 plaque radiotherapy (PRT). This study included 243 patients with unilateral UM treated at Beijing Tongren Hospital from 2007 to 2020. Of these, 119 initially received PRT, followed by enucleation 2 months-9 years later. We retrospectively examined the histopathological features of enucleated ocular tissues to investigate microscopic differences based on treatment methods and reasons for secondary enucleation. Compared with 124 primary enucleations, eyes after PRT were more likely to show tumour diffuse distribution; had more tumour cell necrosis and more inflammation. In addition, eyes after PRT had a higher frequency of sclera invasion, optic nerve invasion by the tumour and neovascularisation of the iris. Histopathologically, 55 eyes (46%) were removed due to local control failure. Compared with eyes enucleated because of severe radiotherapy complications, eyes enucleated for local control failure had tumours invading the optic disc and ciliary body more frequently, pathological mitosis and the proportion of tumour diffuse distribution were higher. Eyes with radiotherapy complications had more tumour tissue necrosis and more neovascularisation of the iris. By observing the pathological features, we regrouped the patients who underwent secondary enucleation after PRT. These differences in histopathology may represent tissue effects of radiotherapy radiation or features related to tumour progression and growth. Tumour insensitivity and progression after PRT clearly increased the risk of metastasis-related death. Some pathological microscopic features may be important prognostic indicators of patients with UM.