Eosinophilic Esophagitis (EoE) is a immuno-mediated disease, characterised by a Th-2 food-antigen driven chronic inflammatory response of the esophagus. Main symptoms are dysphagia and food bolus impaction, frequently overlapping with most atypical and general symptoms like heartburn or regurgitation and difficulty to thrive in children. Overall incidence and prevalence of EoE are rapidly increasing. The complete comprehension of pathogenetic and molecular mechanism underlying this complex and relatively new disease is still to be conquered. For this reason, we created this EoE Biobank, in order to collect blood, oral and esophageal tissue samples of proven EoE patients to further exploit new insights of this disease.

Every EoE patient pertaining to the EoE Unit of San Raffaele Hospital in Milan from 1st June 2023 will be enrolled in the EoE Biobank protocol after being adequately informed and after having signed the informed consent during a preliminary visit where also different clinical and demographic variable of each patient will be taken and stored in an anonymus database. Every patient, during the endoscopic examination performed according to clinical practice guideline for his management, will be asked to provide a sample of oral saliva, 5 mL of blood sample (directly withdraw from the previously placed venous catheter) and additional esophageal biopsies from the esophagus, normally performed for the diagnosis or the follow-up of the disease. The collected samples will be stored in Biological Resources Centre (BRC) of the host organization. These sample will later be analyzed "in vitro" in the context of dedicated protocols

Inclusion Criteria:

• EoE diagnosis proven histologically with clinical activity
• Age > 16 years

Exclusion Criteria:

• Not signed informed consent
• No definite EoE diagnosis

Every male or female patient > 16 years pertaining to IRCCS San Raffaele Hospital in Milan