D1.293 - Hidden allergens revealed by prick-to-prick testing: anaphylaxis triggered by black pepper and cumin

Background

Food-induced anaphylaxis in adults may be caused by hidden allergens, particularly in mixed or processed foods. Standard skin prick testing may fail to identify the responsible trigger in such cases. Prick-to-prick testing using native food samples can provide additional diagnostic value.

Case presentation

A 30-year-old man presented with recurrent anaphylactic reactions following consumption of meatballs. The first two episodes occurred shortly after ingestion in association with physical exertion, whereas the third episode developed approximately 45 minutes after consumption without exercise. Symptoms included nasal itching, throat irritation, palmar erythema and pruritus, lip swelling, tongue itching and edema, dyspnea, nausea, vomiting, facial swelling, tremor, and chest tightness. All episodes resolved after treatment with intramuscular adrenaline in the emergency department.

The patient reported a history of tick bite during childhood; however, specific IgE to galactose-α-1,3-galactose was negative. Serum specific IgE testing was positive for black pepper, while tests for other spices, chicken, beef, and lamb were negative. The homemade meatballs consumed contained onion, egg, breadcrumbs, thyme, black pepper, red pepper powder, cumin, and garlic.

Prick-to-prick testing demonstrated positive reactions to raw spiced meatball, black pepper, cumin, and meatball mix; however, raw unseasoned meat, cooked spiced meatballs, red pepper powder, chili flakes, breadcrumbs, and thyme yielded negative results.

An adrenaline auto-injector was prescribed, and the patient was advised to avoid foods with unknown spice content.

Conclusion

This case highlights the diagnostic importance of prick-to-prick testing in adult food-induced anaphylaxis when standard diagnostic approaches are inconclusive. In complex cooked foods, allergen denaturation may obscure the causative trigger. Testing with native food samples enabled identification of black pepper and cumin as the responsible allergens. A detailed clinical history combined with targeted prick-to-prick testing is essential for accurate diagnosis and prevention of recurrent anaphylaxis in adults.