What allergies are commonly associated with cashew anaphylaxis?

Cross-Reactivity Patterns in Cashew Anaphylaxis

Cashew anaphylaxis is most strongly associated with allergies to pistachio, followed by other tree nuts including walnut, hazelnut, and almond due to significant cross-reactivity between these allergens. 1, 2

Primary Cross-Reactive Allergens

• Pistachio shows the strongest cross-reactivity with cashew, as both belong to the same botanical family (Anacardiaceae), sharing similar allergenic proteins 2, 3
• Hazelnut, walnut, and pecan form another group of tree nuts with significant cross-reactivity to cashew 2
• Almond, Brazil nut, and other tree nuts show moderate cross-reactivity patterns with cashew allergens 2, 3

Cross-Reactivity Mechanisms

• Cashew contains three major allergenic proteins (Ana o 1, Ana o 2, and Ana o 3) that share structural similarities with proteins in other tree nuts 1
• Cross-reactivity occurs primarily through shared epitopes on seed storage proteins (albumins and legumins) between cashew and other Anacardiaceae family members 3
• A putative luminal binding protein has been identified as potentially responsible for cross-reactivity between several Anacardiaceae species 3

Clinical Implications

• Among tree nuts, cashew is now the most frequent cause of tree nut-induced anaphylaxis in children, with increasing prevalence from 2007 to 2024 4
• Cashew allergic reactions are frequently triggered by small amounts (<1 teaspoon) and often occur in patients without previous awareness of their allergy 4
• Patients with cashew allergy should be evaluated for potential cross-reactivity with pistachio and other tree nuts due to the high likelihood of multiple tree nut allergies 5, 1

Risk Factors and Comorbidities

• Asthma is a significant risk factor for severe allergic reactions to cashew and other tree nuts 5
• Atopic dermatitis within the first 6 months of life is associated with increased risk of developing tree nut allergies 5
• Approximately 30.4% of children with food allergies have multiple food allergies, which may include cross-reactive tree nuts 5
• Children with existing food allergies have 4 times higher odds of having asthma, which can increase the severity of anaphylactic reactions 5

Diagnostic Considerations

• Skin prick tests and specific IgE testing should be performed to evaluate potential cross-reactivity between cashew and other tree nuts 5
• The severity of cashew allergy cannot be reliably predicted by the magnitude of skin or blood test results 5
• Oral food challenges in controlled medical settings may be necessary to confirm specific allergies when cross-reactivity is suspected 6

Management Implications

• Patients with cashew allergy should be prescribed two epinephrine autoinjectors due to the high risk of severe reactions 5, 6
• Delayed administration of epinephrine has been implicated in contributing to fatalities from tree nut-induced anaphylaxis 5, 6
• Patients should be observed for 4-6 hours after treatment for cashew-induced anaphylaxis, as biphasic reactions can occur in 1-20% of cases 5, 6
• Comprehensive avoidance of both cashew and pistachio is typically recommended due to their strong cross-reactivity 1, 2

Emerging Research

• Epicutaneous immunotherapy (EPIT) has shown promise in reducing IgE-mediated allergic reactions in mouse models of cashew allergy 7
• Research into simultaneous introduction of multiple foods during oral immunotherapy is being investigated for patients with multiple tree nut allergies 5