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Meet Rudi

Rudi, an 8-year old boy with a history of rhinoconjunctivitis during tree pollen season and asthma exacerbations during infections and exertion, comes to see you because he is now also experiencing itching in the mouth when eating hazelnuts. His mother is sensitized to tree nuts and is worried that Rudi is, too.

His healthcare professional conducts a full clinical history and physical examination and decides to test using specific IgE testing.

Patient history

Family history 

  • Mother, allergic to tree nuts 

  • Younger brother, allergic to egg, milk, peanut, tree pollen, cat and dog 

Personal history

  • Rudi had eczema from 6 months of age until he started school
  • Asthma attacks during infections and exertion 
  • Rhinoconjunctivitis during tree pollen season 

Clinical diagnosis

Tree pollen, peanut, tree nut and pet dander allergy

His previous healthcare professional recommended that Rudi strictly avoid peanut and tree nuts and use oral antihistamines during tree pollen season, as well as symptomatic treatment with inhalant long-acting ß2-agonists and corticosteroids.  

At 4 years SPT results
Test Type Results
Birch Whole Allergen +3
Peanut Whole Allergen +4
Hazelnut Whole Allergen +1
Cat Whole Allergen +4
Dog Whole Allergen +1

New Test Results

Based on these results, his healthcare provider decides to perform testing with allergen components.

ImmunoCAPTM results (kUA /l)
Test Type Results
Birch Whole Allergen 23.1
Peanut Whole Allergen 7.3
Hazelnut Whole Allergen 12.4
Cat Whole Allergen 10.2
Dog Whole Allergen 4.2

These results, together with Rudi's case history and symptoms, may help his healthcare professional confirm the diagnosis.

ImmunoCAP results (kUA /l)
Test Type Results
Ara h 1 Allergen Component 0.2
Ara h 2 Allergen Component 4.3
Ara h 3 Allergen Component <0.1 
Ara h 8 Allergen Component 1.4
Ara h 9 Allergen Component <0.1 
Cor a 1 Allergen Component 12.8
Cor a 8 Allergen Component <0.1 
Cor a 9 Allergen Component <0.1 
Cor a 14 Allergen Component <0.1

Differential Diagnosis

Rudi’s sensitization to the peanut storage protein Ara h 2 shows that Rudi has an increased risk for severe reactions if eating peanuts.1 Strict avoidance of peanut is therefore recommended. 

Rudi’s birch allergy gives rise to cross-reactivity with the PR-10 protein Cor a 1 in hazelnut, and the itching in Rudi’s mouth when eating hazelnuts may originate from the pollen-food allergy.2-4

Rudi’s sensitization to birch pollen is confirmed, continue with current medication.

Refined diagnosis:

Primary peanut allergy and birch allergy

Healthcare professional's management plan

  • Rudi's healthcare professional was advised that an open challenge with hazelnut might reduce the fear of severe reactions to hazelnut based on the family history

  • Rudi was advised to strictly avoid peanuts and always carry his emergency adrenaline autoinjector
  • Rudi's healthcare professional arranged follow-up education and training on autoinjector use for Rudi and his family
  • Rudi's healthcare professional advised him to continue to use antihistamines for the birch-pollen symptoms, starting treatment two weeks before the season

New diagnosis:

Birch pollen, peanut and pollen-food allergy

Follow Up

Rudi is fit and well. His autoinjector technique is satisfactory.

The people, places and events depicted in these case studies and photographs do not represent actual patients, nor are they affiliated in any way with Thermo Fisher Scientific.  

  1. Matricardi PM,  et al. EAACI Molecular Allergology User’s Guide. Pediatr Allergy Immunol. 2016: 27: (suppl23): 1–250.
  2. Masthoff LJ, et al. Sensitization to Cor a 9 and Cor a 14 is highly specific for a hazelnut allergy with objective symptoms in Dutch children and adults. J Allergy Clin Immunol. 2013;132:393-9.
  3. Kattan JD, et al. Clinical reactivity to hazelnut may be better identified by component testing than traditional testing methods. J Allergy Clin Immunol Pract. 2014;2:633-4 e1.
  4. Faber MA, et al. Cor a 14: missing link in the molecular diagnosis of hazelnut allergy? Int Arch Allergy Immunol. 2014;164:200-6.