[Eosinophilic inflammation of the digestive tract]

Eosinophilic inflammation of the digestive tract is an inflammatory disease characterized by extensive infiltration of eosinophils into the gastrointestinal tract. It can be either a primary disorder of the digestive tract or be secondary to another cause of tissue eosinophilia. Primary disorders include eosinophilic esophagitis (OE) and eosinophilic gastroenteritis (GEEo). These are 2 rare pathologies considered to be diseases related to a Th2-mediated food allergy. The role of the pathologist is twofold: (1) he must make the diagnosis of tissue esosinophilia and propose the various causes, knowing that a secondary cause is the most frequently observed; (2) identify the abnormal number of polymorphonuclear eosinophils, which implies knowing the normal distribution of eosinophils in the different digestive segments. To carry the diagnosis of EO, the threshold of polymorphonuclear eosinophils must be ≥ 15/fields × 400. There is no predefined threshold concerning the other segments of the digestive tract to carry the diagnosis of GEE_O. In addition, to make the diagnosis of primary digestive tissue eosinophilia, the patient must be symptomatic with histological evidence of eosinophilia and have ruled out all secondary causes. The main differential diagnosis of OE is gastroesophageal reflux disease. The differential diagnoses of GEEo are multiple, including primarily drugs and parasitic infections.