Is it melanoma-associated retinopathy or drug toxicity? Bilateral cystoid macular edema posing a diagnostic and therapeutic dilemma

PURPOSE: To report the clinical presentation, multimodal imaging, and management of a patient with metastatic melanoma who presented with cystoid macular edema (CME). OBSERVATIONS: We report a case of a 71-year-old Caucasian male with metastatic melanoma who presented with bilateral cystoid macular edema after being on treatment with a programmed T cell death ligand 1 inhibitor, MPDL3280, for 1 year. Multimodal imaging techniques, including color fundus photographs, autofluorescence, spectral domain optical coherence tomography (OCT), fluorescein angiography (Spectralis, Heidelberg, Germany), and spectral-domain OCT angiography (Zeiss; California, USA) were performed to evaluate the etiology of his CME and to monitor his response to treatment. Clinical examination and multimodal imaging revealed 1 + chronic vitreous cells, an epiretinal membrane, and mild macular edema in both eyes. Fundus autofluorescence showed paravenous hypoautofluorescence in the right eye and scattered hypoautofluorescent spots in the left eye. Optical coherence tomography angiography (OCTA) revealed mild drop out of superficial vessels in the peri-foveal region bilaterally. These findings were concerning for melanoma-associated retinopathy, drug-related uveitis, or activation of a previous chronic autoimmune process. The patient was started on prednisone 30 mg oral daily and ketorolac tromethamine 0.5% 1 drop four times daily. He was then treated with bilateral sustained-release dexamethasone intravitreal implants (Ozurdex). He had complete resolution of CME, and was tapered off of oral steroids within 6 weeks. CONCLUSIONS AND IMPORTANCE: Melanoma-associated retinopathy can be accompanied by CME, which presents a diagnostic and therapeutic dilemma in cases where a new drug has been recently initiated. By treating the condition locally, the ophthalmologist may be able to taper systemic immunosuppression more quickly.