Autoimmune Retinopathy Caused by Anti-Paraneoplastic Antigen MA2: A Case Study

Autoimmune retinopathy is a cause of unexplained visual impairment and visual field impairment, which are often related with life-threatening cancers. Here, we report a case of autoimmune retinopathy positive for anti-paraneoplastic antigen MA2 (PNMA2) antibody in serum. Visual acuity and field were impaired, and OCT and ERG were performed. No abnormalities were observed in OCT, but a marked decrease in pyramidal response was observed in ERG. Paraneoplastic antigen-related antibodies in the serum were tested, and PNMA2 was positive. Systemic evaluation to search for the presence of cancer was conducted by specialists treating cancer. However, cancers were not detected, but bladder and prostate cancer were identified 3 years later, and anti-PNMA2 antibodies were again positive in the serum. Although there have been no reports on PNMA2-related retinopathy, the possibility of the paraneoplastic syndrome should be kept in mind when retinopathy of unknown cause is observed.