Eosinophilic esophagitis induced by sublingual immunotherapy with cedar pollen: a case report

Eosinophilic esophagitis (EoE) is a chronic inflammatory disease associated with eosinophilic infiltration of the esophageal mucosa mostly due to exposure to allergens. However, the causes and pathogenesis of EoE are not fully understood. We encountered a case of EoE that was triggered by sublingual immunotherapy (SLIT) for cedar pollen allergy. A 40-year-old man who was treated with Japanese cedar pollen tablet SLIT for cedar pollen allergy developed heartburn 3 weeks after the initiation of the treatment. He took vonoprazan for the heartburn, but the heartburn did not improve. Then, esophagogastroduodenoscopy was performed; it revealed longitudinal furrows and white spots on the esophageal mucosa, decreased vascular permeability, and erosions. Consequently, the patient was diagnosed with EoE. Heartburn and chest discomfort disappeared 1 week after the discontinuation of Japanese cedar pollen tablet SLIT, and the patient tested positive for drug allergy to Japanese cedar pollen tablet SLIT. In this study, we found that if heartburn persists during SLIT for cedar pollen allergy, and does not improve on administration of vonoprazan or proton pump inhibitors, EoE should be suspected. In addition, the occurrence of EoE due to drug allergy is indicated.