Prevalence of Hepatocyte Growth Factor and Autoantibodies to α-HGF as a New Etiology for Bilateral Diffuse Uveal Melanocytic Proliferation Masquerading as Neovascular Age-Related Macular Degeneration

OBJECTIVE: The goal was to test the hypothesis that high serum hepatocyte growth factor (HGF) and retinal autoantibodies against α-HGF contribute to the pathology of bilateral diffuse melanocytic proliferation (BDUMP). METHODS: Case report of an elderly diagnosed with neovascular age-related macular degeneration (n-AMD) treated with bilateral Bevacizumab injections. Examination included comprehensive ophthalmic examination and images obtained by fundus photography, fundus autofluorescence, fluorescein angiography, spectral-domain optical coherence tomography (OCT), and B-scan ultrasonography. The levels of HGF and circulating HGF receptor (c-MET) were measured in the serum by ELISA and anti-retinal autoantibodies by western blotting. RESULTS: Patient received Bevacizumab injections for presumed n-AMD and had a history of papillary renal cell carcinoma stage 4 with a tumor containing gene mutation Y1230C in the mesenchymal-epithelial transition factor (MET). Visual acuity was 20/200 OD and CF OS. Multimodal imaging was consistent with BDUMP. Plasma exchange therapy was recommended but could not be started until 10 months later due to deterioration in his medical condition. Pre- and post-plasma exchange sera demonstrated anti-retinal autoantibodies against 69-kDa protein of the same molecular weight as the α-HGF. Serum autoantibodies reacted with purified recombinant α-HGF on the blot. CONCLUSIONS: BDUMP can mimic n-AMD, which can delay treatment. Plasma exchange resulted in resolved inflammation, resolution of exudative detachments and improved vision after cataract surgery. Consideration of the tumor genetics led to the recognition of elevated HGF levels and autoantibodies to α-HGF (anti-69-kDa), which suggested a new pathogenic mechanism of BDUMP. We believe that therapy with tyrosine kinase inhibitors and a checkpoint inhibitor may contribute to the high HGF levels and subsequent immune response.