A database analysis and review of histological slides (retrospective) and a patient questionnaire analysis (prospective) will be conducted in Bern (Switzerland) to evaluate the efficacy and safety of esophageal dilation and its effect on the underlying eosinophilic inflammation in patients with Eosinophilic Esophagitis. This trial is investigator driven.

Eosinophilic esophagitis (EE) is a chronic, increasingly recognized disease of the esophagus, clinico-pathologically characterized by a proton-pump-inhibitor resistant, dense esophageal eosinophilia in combination with esophagus-related symptoms. Patients suffer mainly from dysphagia, a feared long-term complication is the evolution of esophageal stenoses leading to food-bolus impaction that have to be removed endoscopically. Anti-inflammatory therapy with systemic or topical corticosteroids have shown to be efficacious in children as well as in adults. However, relapses occur in general soon after the cessation of this medication. In addition, several studies have demonstrated that in adults with active EE dilation is an alternative safe and efficacious therapeutic option. Surprisingly, the symptom-free period seems to be much longer after this procedure than after medical treatment. Today, the selection of these two procedures depends more on local practices than on evidence based data, because robust data are lacking. Furthermore, there are concerns regarding the risk of the dilation-procedure (possible esophageal perforations and major bleeding). Furthermore, it has not yet been assessed if dilation changes the underlying eosinophilic inflammation. If not, investigations should be performed to evaluate if long-term anti-eosinophilic therapy is able to change the natural course of the disease and reduce the stricturing complications.

Inclusion criteria for retrospective Database analysis:

• Adult patients with - according to the database inclusion criteria - confirmed active EE, having

  1. Pre-dilational upper endoscopy (EGD) including histology and
  2. Dilation and
  3. Post-dilational EGD/Histo

• Definitions: Active EE is defined as

  1. Symptoms of dysphagia on almost each intake of solid food when off anti-inflammatory therapy or dietary restriction;
  2. Presence of an eosinophilic tissue infiltration with a peak cell density of >24 eosinophils per hpf x 400 on histology of esophageal biopsies.

• Inclusion criteria for additional, prospective, comprehensive histologic and immunologic

• Work-Up: "Comparable" time frame between baseline and post-dilational biopsy sampling

Exclusion criteria:

• Therapy with anti-eosinophilic medications 12 weeks prior to pre-dilational EGD and dilation respectively and between dilation and post-dilational EGD/Histo.

Patients with Eosinophilic Esophagitis referred to gastroenterologists in whole Switzerland working in private practice and in secondary and tertiary referral centers (Departments of Gastroenterology in hospitals)