This protocol addresses a central hypothesis that fibrostenotic Eosinophilic Esophagitis (EoE) is characterized by abnormal esophageal structure and compliance compared to non fibrostenotic EoE and that distinctive cellular and molecular profiles predict the fibrostenotic phenotype. This study aims to define and assess the changes that occur in the structure and dynamics of the esophageal wall in pediatric Eosinophilic Esophagitis along with characterizing the histologic and molecular patterns in fibrostenotic EoE.