## 2 Case Report  
A \(1\)-year-old girl was referred to our hospital with a \(3\)-month history of diarrhea and weight loss. She was fed a mixed diet (breast and formula milk) from birth, beginning with rice and soybeans at \(6\) months and progressing to cows' milk, wheat, and chicken eggs (yolk and white) at 8 months. She did not develop anaphylactic symptoms with formula milk and cows' milk intake. There were no accompanying signs and symptoms related to other organs, such as mild eczema, skin dryness, or frequent upper respiratory tract infection due to cows' milk allergy. Neither she nor anyone in her family had allergic diseases, such as atopic dermatitis or asthma. At 9 months of age, she developed vomiting, diarrhea, and anorexia; her previous diagnosis was infectious gastroenteritis and postereritis syndrome. One month before her transfer to our hospital, she was admitted to the previous hospital because her symptoms did not improve for two months, and her weight loss progressed. During the 2 months prior to her admission, her diet was unrestricted. Although her vomiting improved after a few days of fasting, oral intake of elemental diets, formula milk, or rice porridge resulted in repeated diarrhea. Upon admission to our hospital, her physical examination revealed the following: height, 69.0 cm (standard deviation [SD] \(-\)2.2); bodyweight, 6641 g (SD \(-\)2.8), 999 g lesser than the weight measured 3 months ago; body temperature, 37.1 \({}^{\circ}\)C; heart rate, 96 beats per minute; and blood pressure, 88/50 mmHg. Her blood test results were as follows: white blood cell count, 16,900/mL (normal range [NR]: 7000-15,000); eosinophil percentage, 2.0% (NR: <5.6); hemoglobin, 9.9 g/dL (NR: 13.7-16.8); and platelet count, 679 \(\times\) 10\({}^{3}\) cells/mL. Her laboratory test findings were as follows: total protein, 6.4 g/dL (NR: 6.8-8.1); albumin, 3.9 g/dL (NR: 4.1-5.1); aspartate aminotransferase, 35 IU/L (NR: 20-45); alanine aminotransferase, 17 IU/L (NR: 4-24); blood urea nitrogen, 7.4 mg/dL (NR: 8-20); C-reactive protein, 0.47 mg/dL (NR: <0.03); sodium, 135 mEq/L (NR: 137-147); potassium, 3.6 mEq/L (NR3.6-5.2); bicarbonate, 19.1 mmol/L (NR: 21.0-27.0); and lactic acid, 21 mg/dL (NR: 4-16). At this time, a sufficient number of calories, amino acids, and fat was being administered intravenously. The serum IgE level was 1028 IU/mL (NR < 30), and radioallergosorbent tests were positive for milk (63.7 UA/mL class 5), casein (9.8 UA/mL class 3), alpha-lactalbumin (51.6 UA/mL class 5), egg white (58.8 UA/mL class 5), egg yolk (10.8 UA/mL class 3), ovomucoid (13.2 UA/mL class 3), wheat (14.5 UA/mL class 3), and soybean (1.3 UA/mL class 2). Skin prick tests were not performed to confirm the results of specific IgE test. Immunoglobulin (Ig) levels (IgG, 954 [NR 357-989] and IgM, 89 [NR 29-190]) and lymphocyte subset ratios were normal. Fecal eosinophil tests were negative, and no infection was detected in stool culture tests. Stool adenovirus, rotavirus, and norovirus antigen tests were negative. Imaging and endoscopy examinations were performed to determine the cause of the prolonged diarrhea. Abdominal computed tomography and ultrasound examinations revealed no abnormalities in the small intestine; the large intestine was dilated but no wall thickening was observed, suggesting nonspecific enteritis. An EGD showed no macroscopic abnormalities from the esophagus to the duodenum. However, histopathology of the duodenum mucosa revealed the loss of mucosal villous structure, crypt hyperplasia (Figure 1A,B), crypt apoptosis (Figure 1C), and lymphocyte and eosinophil infiltration (<20 eos/hpf) into the lamina propria, with partially formed crypt abscesses (Figure 1D). Total colonoscopy showed no abnormal macroscopic findings; however, histopathology of the colonic mucosa revealed erosion of the mucous membranes; cryptitis with decreased goblet cells, fibrosis, plasma cells, and lymphocytes; and some eosinophil infiltration (<20 eos/hpf) into the lamina propria.