A case of eosinophilic enteritis-usefulness of electron microscopy in differential diagnosis-

A case of eosinophilic enteritis was reported. A 25-year-old female came to the hospital because of epigastric pain and diarrhea after delivery. There was a history of allergic rhinitis. Laboratory data revealed increased eosinophil count (34%) in peripheral blood and a elevated serum IgE level (430 IU/ml). Malignant cells were not found in bone marrow. Ascites or splenomegaly was not found by CT scan. Endoscopy revealed erosive gastritis in antrum and minimal edematous mucosal changes in duodenum and rectosigmoidal colon. Barium enema did not show any abnormal findings. Biopsies obtained from the rectosigmoidal colon revealed edema in the lamina propria and mild infiltration of the mucosa with eosinophils. The submucosa appeared to be spared from the eosinophilic infiltration. On the other hand, the duodenal biopsies suggested non-specific inflammation of mucosa with infiltrations of inflammatory cells including neutrophils and eosinophils. The esophageal and gastric biopsies revealed no mucosal infiltration of eosinophils, either. Neither eggs nor parasites were found in feces and biopsy specimens. Although differential diagnosis was difficult because eosinophilic infiltrations were seen only slightly, electron microscopical findings showed inflammatory changes around eosinophils which suggest that eosinophils were responsible to mucosal injury. From these findings, the diagnosis is determined to be “predominant mucosal layer disease” of eosinophilic enteritis according to Klein's classification. Electron microscopy was useful to distinguish the disease from other inflammatory bowel diseases and collagen diseases which clinical and pathological manifestation may mimic those of eosinophilic enteritis at the initial stage.