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.

Inclusion Criteria:

• Scheduled to undergo a clinical upper endoscopy with biopsy

Exclusion Criteria:

• Known connective tissue disorder
• Increased risk of bleeding
• Inflammatory bowel disease, celiac disease, eosinophilic gastroenteritis, or any autoimmune disease
• Other esophageal disease including known achalasia; history of caustic ingestion, esophageal surgery esophageal stricture for other known reason or other esophageal injury.
• Use of oral or intravenous steroids in the preceding 60 days. (Swallowed topical fluticasone, budesonide, etc not included as exclusion criteria.)

Children, ages 5 to 18 years, scheduled to undergo a clinical upper endoscopy with biopsy for suspected or confirmed Eosinophilic Esophagitis.