Eosinophilic esophagitis is associated with a number of histologic changes in the esophageal mucosa.
The most important finding is an increase in eosinophils in the mucosa. The cut-off varies between authors but >= 15 eosinophils per high power field is used by the American College of Gastroenterology (ACG). The distribution may not be uniform, so multiple biopsies may be necessary to identify.
Additional changes related to eosinophils:
(1) eosinophil microabscesses
(2) eosinophil degranulation (extracellular eosinophilic granules)
(3) presence of eosinophils at the luminal surface
(4) peripapillary eosinophilia
Changes to the mucosal epithelium:
(1) basal cell hyperplasia
(2) spongiosis
(3) epithelial desquamation
(4) papillary elongation
(5) fibrosis of the lamina propria
