Supplementary Material for: Multimodal Imaging Features of Bilateral Diffuse Uveal Melanocytic Proliferation: A Systematic review of 82 Patients

Background: Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a rare paraneoplastic syndrome characterized by proliferation of benign melanocytes throughout the uveal tract. Our purpose was to quantify the prevalence of multimodal imaging findings in BDUMP and identify features that most reliably characterize this rare paraneoplastic syndrome. Summary: We conducted a systematic review following PRISMA 2020 guidelines, searching PubMed/MEDLINE, Web of Science, and Embase through September 2025. We included case reports and series providing patient-level data on BDUMP with associated imaging. Prevalence rates were calculated using a documented denominator approach with 95% Wilson score confidence intervals. Sixty-seven studies encompassing 82 patients were included. Gynecologic (25.9%), gastrointestinal (22.2%), and lung (17.3%) cancers were most common. Optical coherence tomography (OCT) revealed RPE irregularities in 91.8% and subretinal fluid in 90.2% of patients, exceeding the prevalence of classical orange-red patches on fundus photography (82.6%). Fundus autofluorescence showed alternating hypo/hyperautofluorescence in 76.6%. Choroidal thickening was present in 88.9% on ultrasonography. Bacillary layer detachment was identified in 16.4% of cases. Key messages: OCT-based structural abnormalities are more consistently present than Gass's classical funduscopic signs. These quantitative data may assist earlier recognition of BDUMP and suggest that updated diagnostic criteria should incorporate multimodal imaging findings.