Bilateral Diffuse Uveal Melanocytic Proliferation Masquerading as Refractory Subretinal Fluid Due to Peripapillary Pachychoroid Syndrome

We describe a case of peripapillary pachychoroid syndrome (PPS) that appeared resistant to conventional treatment and was subsequently diagnosed as bilateral diffuse uveal melanocytic proliferation (BDUMP) based on fundus autofluorescence (FAF) images. A 79-year-old man presented with vision loss in both eyes and was initially diagnosed with PPS based on optical coherence tomography, fluorescein angiography, and indocyanine green angiography findings. The patient underwent photodynamic therapy in both eyes, photocoagulation in the left eye, and 2 mg aflibercept injections in both eyes. Although he responded to the initial treatments, the response gradually diminished with subsequent injections. Due to the progression of his cataracts, the patient underwent cataract removal surgery. He was later diagnosed with BDUMP based on subsequent FAF images, which revealed characteristic ocular fundus findings known as giraffe-like patterns. Subsequent systemic evaluation revealed prostate cancer. BDUMP can masquerade as PPS or neovascular age-related macular degeneration (n-AMD), resulting in delayed diagnosis and treatment, and should be considered in the differential diagnosis of cases where PPS or n-AMD is refractory to conventional treatment, even in the absence of a known malignancy.