Severe Dysphagia With Eosinophilic Esophagitis Pattern of Injury Related to Pembrolizumab Therapy.

While immune checkpoint inhibitor (ICI) therapies are effective treatments for many cancers, ICI therapies are associated with immune-related adverse events. We present a 67-year-old man with non-small cell lung carcinoma, who developed severe dysphagia with biopsies from an esophagogastroduodenoscopy showing histopathology consistent with eosinophilic esophagitis while on ICI maintenance therapy with pembrolizumab. The patient's symptoms worsened despite standard therapy. However, he had complete resolution of dysphagia symptoms once pembrolizumab was discontinued. While immune-related adverse events affecting the gastrointestinal system are increasingly recognized, ICI-associated eosinophilic esophagitis is a rare entity.