Extrascleral Tumor Extension Associated with Localized Scleral Melt following Plaque Brachytherapy for Uveal Melanoma: Clinical and Histologic Findings

Abstract

<b><i>Background/Aims:</i></b> Our study aims to better characterize the clinical and histopathologic features of eyes with extrascleral uveal melanoma associated with scleral melt following brachytherapy. <b><i>Methods:</i></b> A retrospective review was performed on patients who had undergone ¹²⁵I (iodine-125) brachytherapy for uveal melanoma at our institution between 1992 and 2015. Patients with postradiation scleral necrosis who required enucleation were identified, and an analysis including a review of histopathology results was performed on those cases. <b><i>Results:</i></b> A total of 301 patients underwent plaque brachytherapy for uveal melanoma, of whom 31 required eventual enucleation. The histologic analysis showed extraocular extension through full-thickness scleral discontinuities in 6 cases. All but 1 (5 of 6) of these eyes exhibited either mitotic figures or Ki-67 positivity. Mitotic figures were noted in 4 specimens, including 3 eyes exhibiting mitoses within or adjacent to the extrascleral portion of the tumor. Two eyes exhibiting mitoses, as well as the case with Ki-67 positivity, also had clinical evidence of tumor regrowth. <b><i>Conclusion:</i></b> We found evidence of mitotic activity at the area of scleral discontinuity in some eyes with and in some without clinical evidence of tumor regrowth. Protruding pigmented material in areas of scleral necrosis after plaque brachytherapy may represent actively proliferating tumors even without internal evidence of tumor regrowth.