Nothing fun about food protein-induced enterocolitis to fungi: A case report

Abstract

Food protein-induced enterocolitis syndrome (FPIES) is a non-IgE-mediated hypersensitivity reaction known to be triggered by a variety of foods. We present a rare case of a 10-year-old boy with no history of atopy who experienced multiple episodes of delayed, profuse vomiting and lethargy following mushroom ingestion, beginning in infancy. Diagnosis of acute FPIES was confirmed through an oral food challenge, with negative serum IgE and skin prick testing supporting a non-IgE-mediated mechanism. This case represents only the second reported instance of mushroom-induced FPIES in the pediatric population. Given the distinct biological properties of fungi and their increasing use as alternative protein sources, mushrooms may represent an emerging and underrecognized trigger of FPIES, warranting increased clinical awareness.

Food protein–induced enterocolitis (FPIES) is a non–immunoglobulin E (IgE) mediated food hypersensitivity with heterogenous features on presentation, with variable onset and severity. Although initially thought to be a rare condition, it is now known to have a prevalence between 0.01 and 0.7% in Western countries, affecting approximately one million individuals within the United States alone.¹ FPIES was initially described in infants in the setting of cow’s milk and soy consumption, but it is now known to be associated with a plethora of triggers, including solid foods. Rice and oat are recognized as the most common solid food triggers of FPIES, although many foods have been described.² We present a rare case of FPIES due to mushroom ingestion, which has been reported only once before in the pediatric population, and discuss the unique aspects of fungi as a trigger of FPIES.³

CASE REPORT

A 10-year-old boy without a history of atopy presented to our clinic for evaluation of profuse emesis after mushroom and walnut ingestion. His initial presentation was at 10 months old when, within 90 minutes of ingesting a veggie burger that contained mushrooms and walnuts, he developed forceful repetitive emesis followed by sleepiness. No interventions were required, and he returned to baseline with observation. He had a similar episode after ingestion of plain sauteed mushrooms, with no walnut exposure, at 1 year old and parents were told to strictly avoid both mushrooms and walnuts. At 2 years old, he had an accidental exposure to mushroom broth after ingestion of vegetarian chili, after which he again developed profuse emesis and was noted to be lethargic, again with no walnut exposure. He was definitively diagnosed with walnut FPIES through oral food challenge (OFC) at 3 years old. Parents did not mention other symptoms or concomitant illness at the time of reported reactions.

Serum IgE levels for mushroom and walnut were obtained by the primary care provider and were undetectable. The patient also underwent skin-prick testing to peanuts, pecans, walnuts, hazelnuts, and mushrooms at an outside institution, all of which were negative results. Given a suspicion for a non–IgE-mediated reaction, inpatient mushroom OFC was scheduled. Two and a half hours after ingestion of a total mushroom aliquot of 0.3 g of protein/kg, the patient presented with forceful and repetitive emesis with associated pallor, followed by lethargy. A complete blood cell count showed an increase in his absolute neutrophil count pre- and post-challenge from 3.05 × 1000/µL to 19.14 × 1000/µL. The patient was given one dose of ondansetron for management of emesis and had complete resolution of symptoms within 5 hours of symptom onset. Given that one major (delayed vomiting) and three minor criteria (lethargy, pallor, >1500 cells/mL increase from baseline neutrophil count) were met, acute FPIES was diagnosed and continued avoidance of mushroom was recommended, with a plan for repeated walnut OFC to assess for resolution. Informed parental consent was obtained for the publication of this report.

DISCUSSION

Mushrooms, classified as fungi, are biologically and nutritionally distinct from plant- and animal- derived foods. Compared with plants and animals, these organisms primarily rely on decomposed complex carbohydrates for energy and possess a unique cellular structure, including a cell wall composed of mannoproteins, chitin, and β-glucans.⁴ Proteins with unique features, such as lectins, protease inhibitors, and hydrophobins, have also been identified in fungi.⁵ Nutritionally, fungi represent a unique food group characterized by high protein, high fiber, and low fat content, which makes them of particular interest in the context of global concerns with regard to population growth and protein availability.⁶ It is estimated that, within the fungi kingdom, there are ∼2000 types of edible mushrooms.⁴ Recent research showed that the protein content of the most commonly ingested mushrooms can range from 8.5/100 × g − 36.9 × g/100 × g.⁶ By comparison, the protein content of some of the most common triggers of FPIES such as eggs and soy have been known to be ∼12.58/100 × g and 36.49/100 × g, respectively.^7,8

The clinical spectrum of hypersensitivity reactions to fungi is broad and includes types I, II, III and IV hypersensitivity reactions.⁹ The majority of documented reactions to fungi, however, are IgE-mediated and associated with cutaneous and/or respiratory symptoms. Results of some studies suggest an association between fungal aeroallergens and IgE-mediated reactions after mushroom ingestion such as oral allergy syndrome and anaphylaxis.¹⁰ Non–IgE-mediated hypersensitivity reactions to fungi are rare, with documented cases primarily associated with aeroallergens rather than fungal ingestion.

To our knowledge, there has been only one previous report of FPIES triggered by mushrooms in the pediatric population.³ It is our understanding that these two cases represent the first reported cases of patients with fungi-triggered non–IgE-mediated reactions in the pediatric population. Compared with other FPIES triggers, fungi are unique in their biologic structure given their unique protein composition. Nutritionally, they overlap with previously identified triggers in their total protein content. Global concerns about population growth and nutritional protein availability have sparked interest in edible fungi as an alternative meat source, positioning them to become emerging triggers of FPIES in the near future.

CONCLUSION

This case represents the second reported instance of FPIES triggered by fungal ingestion. Given their distinct biologic structure and nutritional profile, fungi represent a unique class of FPIES triggers. As interest in alternative protein sources grows, fungi may emerge more frequently as a cause of FPIES.