Cancer-Associated Retinopathy as the Sole Presenting Sign of Small Cell Lung Cancer: A Case Report.

Paraneoplastic syndromes are a rare group of disorders involving an immune reaction to cancer. Since paraneoplastic syndromes can impact any organ system, presenting symptoms can vary dramatically, which can make them difficult to detect and diagnose. Paraneoplastic visual symptoms are a rare and potentially early manifestation of an underlying malignancy. This case report describes a patient who presented with progressive, bilateral vision loss. Neuro-ophthalmology evaluation revealed severe bilateral outer retinal atrophy on optical coherence tomography and vitritis. This raised a concern for cancer-associated retinopathy, a visual paraneoplastic process. Further imaging revealed a spiculated lung mass and led to a diagnosis of small-cell lung cancer. Unfortunately, despite early initiation of corticosteroids and intravenous immunoglobulin, he did not have significant visual improvements. However, he did have a significant initial tumor response to carboplatin, etoposide, and atezolizumab. Ultimately, astute recognition of this paraneoplastic process led to an early diagnosis and initiation of treatment for small cell lung cancer. We describe this case with the goal of helping other providers consider visual paraneoplastic processes among their differential diagnoses, especially among patients with unusual presenting symptoms or who have underlying risk factors for malignancy.