Pembrolizumab-Induced Choriocapillaritis and Orbital Inflammation: A Case Report.

Immune checkpoint inhibitors (ICIs) such as pembrolizumab have significantly extended patient survival in metastatic melanoma; however, they may rarely induce heterogeneous and potentially vision-threatening ocular immune-related adverse events (irAEs). We report a case of a 52-year-old man with metastatic superficial spreading melanoma who, after two years of pembrolizumab therapy, presented with bilateral ocular redness and photopsias. Visual acuity was preserved in both eyes. Fundus examination showed multifocal pigmentary changes. Fundus autofluorescence (FAF) revealed corresponding hypoautofluorescent spots without macular involvement, and indocyanine green angiography (ICGA) demonstrated multifocal hypercyanescent lesions consistent with choriocapillaritis. Orbital MRI demonstrated extraocular muscle enlargement and intraconal fat inflammation suggestive of posterior orbitopathy, without exophthalmos or optic nerve compression. Given the excellent systemic response and preserved vision, a multidisciplinary team elected to continue pembrolizumab, initiate topical corticosteroids, and ensure close ophthalmologic follow-up. Systemic corticosteroids were reserved for potential progression. This rare association of multifocal choriocapillaritis and posterior orbitopathy under pembrolizumab underscores the expanding spectrum of ocular irAEs. Importantly, when findings are mild and vision is preserved, pembrolizumab may be continued with local treatment. Early recognition and close collaboration between ophthalmology and oncology are essential to prevent irreversible visual morbidity while maintaining optimal oncologic outcomes.