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Eye Pain, History of Melanoma
This case features a patient with a history of melanoma presenting with eye pain, ultimately diagnosed with immune checkpoint inhibitor (ICI) orbital side effects.
Imaging overview:
Axial and coronal T1 fat-saturated post-contrast MRI demonstrates enlargement of the extraocular muscles with diffuse orbital enhancement and hyperemia, similar in appearance to thyroid-related eye disease. Posterior scleritis with thickening and enhancement of the sclera is also present. Comparison with axial and coronal T1 fat-saturated post-contrast MRI from two months prior shows interval development of these findings, temporally correlating with initiation of immune checkpoint inhibitor therapy.
Clinical insight:
Immune checkpoint inhibitors work by overcoming T-cell inhibition to facilitate tumor elimination, creating a pro-inflammatory state that can produce immune-related adverse effects across multiple organ systems, including the orbit. Orbital ICI toxicity can manifest as extraocular muscle myositis resembling thyroid eye disease, posterior scleritis with scleral thickening and enhancement, diffuse orbital inflammation, and rarely retinal or choroidal fluid accumulation. Awareness that ICI medications can cause orbital side effects is essential, as these findings can mimic primary orbital disease or orbital metastases in a patient with known malignancy. Correlation with treatment history and comparison to prior imaging are key to making the correct diagnosis.
Case courtesy of Remy Lobo, MD, University of Michigan, University of Utah.