2022 Volume 71 Issue 3 Pages 68-70
Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated gastrointestinal food allergy characterized by repetitive vomiting within 1–4 h and/or diarrhea within 24 h after ingesting the causative food. We herein report a rare Japanese case of rice-induced FPIES. A six-month-old, female, Japanese patient presented to the emergency room (ER) with the complaint of vomiting after feeding. Postprandial vomiting had occurred occasionally since she started ingesting solid food at the age of 5 months. Rice-induced FPIES was suspected only after the fourth ER visit based on the characteristic history of recurrent vomiting occurring 1–2 h after ingesting food containing rice. Allergen-specific IgE testing and a skin prick test with an allergen scratch extract were both negative for rice. During an oral food challenge test (OFC), vomiting was observed after the patient ingested 2 g of rice porridge. Based on the OFC results and the entire clinical course, FPIES due to rice was diagnosed. A lymphocyte stimulation test with rice revealed a significantly elevated stimulation index. Rice-induced FPIES is rarely reported among Japanese infants despite rice being a staple in the Japanese diet. The prevalence of rice-induced FPIES differs greatly among populations, suggesting a multifactorial cause associated with its development. Delays in diagnosis are common in FPIES, and our case demonstrates the importance of obtaining a dietary history of food ingested prior to symptom onset in cases of infantile repetitive vomiting.
Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated gastrointestinal food allergy characterized by repetitive vomiting within 1–4 h and/or diarrhea within 24 h after ingesting the causative food.1 While cow’s milk and soy are common causes of FPIES, grains, including rice, have also been implicated. The frequency of each causative food differs among populations.2,3 While egg yolk-induced FPIES cases are currently on the rise in Japan,2,3,4 only a few cases of rice-induced FPIES have been reported despite rice being introduced into the diet at an early stage of life in the Japanese population.5 We herein report a rare Japanese case of rice-induced FPIES.
A 6-month-old, female, Japanese patient presented to the emergency department with the complaint of vomiting after feeding. She was generally healthy but was born at 37 weeks’ gestation with a birthweight of 2086 g. She was the first child of healthy parents, neither of whom had a history of allergy. Both parents had a normal diet. After a brief period of being fed infant formula while in the hospital, the patient was mainly fed breastmilk. Her height and weight gain were normal according to the standard growth chart for female Japanese infants, and she showed no developmental delay. She began ingesting solid food at the age of 5 months. Postprandial vomiting occurred occasionally from that time. She visited the emergency room (ER) for the first time for repeated vomiting 1.5 h after eating porridge containing rice and pumpkin; however, the vomiting had ceased before her arrival at the ER. On arrival, she appeared well, with no sign of dehydration on physical examination, and was discharged home as a result. She was fed only breastmilk for the next month and had no vomiting during that period. At the age of 7 months, the vomiting relapsed 2 h after ingesting rice water. Although she presented with lethargy, she had no fever, diarrhea, or hematochezia during this episode. After vomiting more than ten times, she visited the ER again and received intravenous fluid replacement for lethargy and tachycardia. Her laboratory data were normal, and no radiographic abnormalities were found on abdominal X-ray or ultrasound. The symptoms resolved rapidly after fluid replacement, and she was discharged home again. After experiencing multiple episodes of vomiting, which required four ER visits in total, she was admitted for further evaluation. Table 1 summarizes the course of symptoms prior to admission. Vomiting occurred every time the patient ingested rice porridge, but not after she ingested other foods, such as sweet potato. She experienced no fever, poor feeding, diarrhea, or hematochezia while at home.
| Episode | Age at onset | Diet before onset | Time from ingestion to symptom onset | Symptoms | Treatment |
| 1 | 6 months | Porridge containing rice and pumpkin | 1 h 30 min | Vomiting | None |
| 2 | 7 months | Porridge containing rice and infant formula |
2 h | Vomiting, lethargy, tachycardia |
Intravenous fluid replacement |
| 3 | 7 months | Porridge containing rice and infant formula |
2 h | Vomiting | None |
| 4 | 7 months | Rice porridge | 2 h 15 min | Vomiting | None |
If she was fed breastmilk, she experienced no vomiting after admission. Critical diseases, such as sepsis, intussusception, malrotation, and metabolic disorders, were considered unlikely based on repeated negative blood test and abdominal ultrasound findings. Based on the characteristic history of recurrent vomiting occurring 1–2 h after ingesting food containing rice, rice-induced FPIES was suspected. Her total IgE was 5.0 IU/mL, and allergen-specific IgE testing yielded a value of <0.10 kUA/L for rice (ImmunoCAP, ThermoFisher Scientific, Uppsala, Sweden). A skin prick test with an allergen scratch extract (Torii Pharmaceutical, Tokyo, Japan) was negative for rice. An oral food challenge test (OFC) with a small dose of rice once per day under close monitoring was then conducted to confirm the diagnosis. She was asymptomatic after ingesting 1 g and 2 g of rice water. Two hours after ingesting 2 g of rice porridge, she became irritable and vomited twice. No rash or wheezing was detected during the test. The patient did not fulfill the stringent diagnostic criteria for FPIES based on the OFC results.1 However, we avoided further testing with an increased amount of rice because of the risk of triggering more severe symptoms and discharged her home with instructions to avoid eating rice. Ingesting milk, soy, wheat, cow’s milk, meat, fish, and vegetables at home caused no symptoms. Based on the OFC results and the entire clinical course, FPIES due to rice was diagnosed. With permission from the patient’s parents, a lymphocyte stimulation test (LST) (SRL, Tokyo, Japan) was performed using rice; the results showed a stimulation index of 1279% (cutoff value: 180%). Informed consent was obtained from the patient’s parents for publication of the details of the case.
Rice-induced FPIES is rarely reported among Japanese infants despite rice being a staple in the Japanese diet. Unlike in Japan, rice is one of the major causes of FPIES in some other countries, including the U.S. and Australia.2,3 Since Ikola6 reported the first case in 1967, the number of patients diagnosed with rice-induced FPIES in these countries has increased. An increase in rice consumption has been cited as a possible factor contributing to the current predominance of rice as a FPIES-triggering food in Australia.7 However, retrospective case series from Italy, where rice is a common weaning food, reported that the proportion of FPIES due to rice was as low as 4%.8,9 Differences in dietary behaviors may explain the variations in FPIES triggers across populations, although genetic and environmental factors undoubtedly contribute to the development of FPIES triggered by rice.10
The LST results in the present case supported the utility of this test, as seen previously with FPIES due to cow’s milk and quail eggs.11,12 LST utilizes the antigen-specific T-cell response, which is implicated in FPIES pathology, and may thus be useful for diagnosis.1,12 More cases are needed to verify the sensitivity and specificity of LST and to enable its application as a biomarker in the diagnosis of FPIES.
Our patient was diagnosed with FPIES due to rice 2 months after the onset of symptoms and after four ER visits. A previous report from the United Kingdom demonstrated a median delay of 4 months in the diagnosis of FPIES, which indicates the difficulty of diagnosing this condition.13 Numerous diseases cause repetitive vomiting in infants, including infections, anatomical gastrointestinal obstruction, and metabolic disorders.1 The current case demonstrates the importance of obtaining a dietary history prior to symptom onset and excluding other critical diseases capable of causing vomiting in infants. If the patient’s dietary history raises suspicion of this condition, rice-induced FPIES should be included in the differential diagnosis even if its prevalence is low.
We thank James R. Valera for his critical reading of the manuscript.
The authors declare no conflicts of interest.
