A rare case of idiopathic hypereosinophilic syndrome involving the oral cavity associated with the esophagus and gastrointestinal tract.

We report the rare case of HES involving oral cavity associated with esophagus, and gastrointestinal tract, which we succeeded in diagnosing precisely through a biopsy specimen obtained from the lip. A 64-year-old man had dysphagia, swelling of the oral mucosa and the posterior cervical muscles, accompanied by an abdominal pain and diarrhea. Peripheral blood cell count showed marked eosinophilia. Computed tomography showed thickening of posterior wall of the pharynx, esophagus, and gastrointestinal tract. Histologic specimen obtained from the lower lip demonstrated a moderate infiltration of eosinophils. His clinical condition was improved by oral prednisolone therapy.