Large Cell Neuroendocrine Carcinoma of the Lung with Cancer-Associated Retinopathy

We report a rare case of large cell neuroendocrine carcinoma (LCNEC) of the lung with cancer-associated retinopathy (CAR). To our knowledge, only two cases of LCNEC with CAR have been reported, one in 1995 and another in 2013. CAR, typically associated with small cell lung cancer (SCLC), is one of the paraneoplastic syndromes with deterioration of visual acuity, visual field constriction, and photophobia. CAR is caused by an autoimmune system reaction against the same antigen in the tumor and retinal photoreceptor cells. To diagnose CAR, genetic retinal dystrophies or any other medical causes of retinopathy should be excluded, but there are no standard diagnostic criteria. Anti-retinal antibodies are known to be positive in CAR patients, and anti-recoverin antibodies are thought to be sensitive and specific to CAR. In our case, anti-recoverin antibodies were not detected by serum tests, but CAR could be diagnosed on the basis of ophthalmological findings including clinical symptoms, electroretinographic findings, and visual field tests. CAR with clinical features of rapid visual disorder should be considered in LCNEC patients as well as in SCLC patients.