Background Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a rare paraneoplastic intraocular disease that causes progressive visual loss in patients driven by an IgG factor associated with an underlying malignancy. Characteristic ocular findings include exudative retinal detachment, rapid cataract formation and uveal melanocytic tumors. Case presentation Here, we presented a patient, whose clinical manifestation was diffusely thickened choroid, shallow anterior chamber, cataract formation and exudative retinal detachment. Histopathologic examination for the biopsies from the choroid during the surgery showed the the tissue might be originated from melanocytes and with the benign biologic behavior. Therefore, the diagnosis for this patient was BDUMP, although there was no obvious history of malignancy until we prepared for this article. Conclusions This was a rare BDUMP clarified by ophthalmic manifestations and histopathologic examination, without clear history of systematic malignancy.