Abstract
BACKGROUND/OBJECTIVES: The purpose of this study is to report cases of choroidal melanoma that developed extrascleral tumour recurrence after treatment with iodine-125 brachytherapy. SUBJECTS/METHODS: In this single-institution retrospective observational case series, all instances of biopsy-confirmed orbital melanoma after known intraocular melanoma were reviewed. Tumour characteristics, clinical course, time to recurrence, cytogenetics of initial tumour and recurrence, and presence of intraocular recurrence were documented. RESULTS: Five cases of orbital melanoma following treatment with plaque radiotherapy are described. Tumour staging was Ia (1), IIa (2), and IIb (2). The primary lesion in four of the five appeared to have undergone complete regression for an average of 2 years, with the orbital melanoma developing after this interval. Recurrence of the intraocular tumour was seen in conjunction with an extrascleral component in two cases. Four cases ultimately underwent enucleation or exenteration; three had evidence of direct extension of tumour through the sclera. Four cases in this series had molecular characteristics associated with high metastatic risk (three patients with monosomy 3, one with BAP1 mutation). CONCLUSIONS: High-risk tumour biology may predispose to late appearance of extrascleral melanoma despite optimal treatment and adequate control of the intraocular tumour. Extended follow-up with detailed orbital examination and imaging is recommended for this population.