D3.213 - Anaphylaxis to Sumac in a Patient with Cashew and Pistachio Allergy: Cross-Reactivity Among Anacardiaceae Species
Case report
Background:
The Anacardiaceae family includes foods such as cashew, pistachio and mango, as well as the less common sumac and pink peppercorn. Cross-reactivity between cashew, pistachio and pink peppercorn has been reported in both serological and clinical observation, though only one clinical case of allergy to sumac has been described in the literature.
Case Report:
We report the case of a 36-year-old female who presented to the Emergency Department (ED) with throat itching and difficulty in breathing after consuming two bites of a meal containing sumac. The patient self-administered antihistamines and two doses of adrenaline prior to arrival. In ED she received prednisolone and observation, then discharged with resolution of symptoms.
The patient has a background of cashew and pistachio allergy (cashew SPT 16x8mm, sIgE 2.27; pistachio SPT 20x8mm), with multiple episodes of reactions requiring adrenaline. Interestingly, the patient reported previous reactions to mango, though SPT and sIgE were negative. SPT also demonstrated sensitivity to sumac (10x6mm) and pink peppercorn (20x10mm). Notably, the triggering meal did not contain cashew, pistachio or mango, implicating sumac as the probable allergen.
The patient tolerates other nuts, including peanuts, walnuts, almonds, and hazelnuts. She has a history of seasonal allergic rhinitis and oral allergy syndrome, with SPT showing sensitivity to grass (9x6mm) and tree pollen (5mm).
Discussion:
This case represents the first reported instance of anaphylaxis to sumac, supporting previous reports of its potential as an allergen in cashew/pistachio allergic patients. As dietary trends evolve, spices such as sumac, commonly used in Middle Eastern cuisine, are increasingly incorporated into restaurant dishes and home cooking. Current labelling regulations do not require additives comprising less than 2% of a food's total mass to be listed as ingredients unless they are one of the 14 most common allergens.
Conclusions:
This case highlights the potential of sumac allergy as a risk to patients with cashew or pistachio allergies. Improved labelling practices and further characterisation of cross-reactivity between members of this plant family may aid patients in personal risk mitigation.
