Sophie, an 8-year-old girl with a history of rhinitis and oral allergy syndrome (OAS), visits her healthcare provider following a recent emergency admission after developing severe angioedema. Sophie recovered well after administration of antihistamines and oral steroids; she did not require epinephrine. Her mother reported that she had muesli containing hazelnut before the onset of symptoms.
She was previously tested for sensitization to respiratory allergens and was diagnosed with birch pollen allergy. Her healthcare provider conducts a full clinical history and physical examination and decides to test using hazelnut components.
After eating a bowl of cereal, 8-year-old Sophie was covered in large hives. What did specific IgE blood testing reveal?
Sophie's test results were:
Test |
Type |
Sophie's Results |
Birch |
Whole Allergen |
+3 |
Hazelnut |
Whole Allergen |
+2 |
Sophie had a negative skin prick test to grass, mugwort, cat, dog, and mite.
Test |
Type |
Sophie's Results |
Birch |
Whole Allergen |
3.4 |
Hazelnut |
Whole Allergen |
0.6 |
Based on history, evaluation, and testing, her previous healthcare provider recommended that Sophie use oral antihistamines during birch pollen season. It’s also recommended to avoid hazelnuts, as the symptoms indicate cross-reactivity between pollen and hazelnut.
These results together with this patient's case history and symptoms, help confirm the diagnosis.
Test |
Type |
Sophie's Results |
Hazelnut |
Whole Allergen |
3.9 |
Birch |
Whole Allergen |
5.3 |
Cor a 1 |
Allergen Component |
2.2 |
Cor a 8 |
Allergen Component |
<0.1 |
Cor a 9 |
Allergen Component |
1.3 |
Cor a 14 |
Allergen Component |
2.0 |
Bet v 1 |
Allergen Component |
4.5 |
Sophie’s severe reaction could be explained by her sensitization to the storage proteins Cor a 9 and Cor a 14, which shows that Sophie has a primary hazelnut sensitization to proteins that can cause severe and systemic reactions.1
Sophie’s birch allergy also gives rise to cross-reactivity with the PR-10 protein Cor a 1 in hazelnut.2
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