D3.346 - From Anaphylaxis to Oral Allergy Syndrome: Multiple Seed Hypersensitivity in a Single Pediatric Patient

Introduction

Edible seeds such as sesame, sunflower, flaxseed, pumpkin, and poppy seeds are increasingly incorporated into daily diets as well as pharmaceutical and cosmetic products due to their rich nutritional profiles and health benefits. With rising consumption, hypersensitivity reactions have also increased.  We report a pediatric case demonstrating oral allergy syndrome triggered by pumpkin and watermelon seeds following recurrent anaphylaxis caused by poppy seed ingestion.

Case Report

A 12-year-old boy presented with immediate itching and numbness of the tongue and throat after consuming pumpkin seeds, without accompanying rash, respiratory distress, or vomiting. His medical history revealed two previous hospitalizations for poppy seed-induced anaphylaxis. He also experienced seasonal allergic rhinitis symptoms during spring over the past three years. Skin prick testing showed no sensitization to inhalant allergens that could cross-react with seeds. Prick-to-prick testing with raw pumpkin seeds yielded a positive was positive with a 13 mm wheal (Figure 1). Pumpkin seeds were eliminated from his diet. Approximately one year later, he returned with similar itching in the tongue and throat after consuming black watermelon seeds; no symptoms occurred when eating watermelon after removing the seeds. Prick-to-prick testing was negative for watermelon pulp and white seeds but positive for black seeds with an 11 mm wheal (Figure 2). Avoidance of poppy, pumpkin, and watermelon seeds was advised.

Discussion

Seed allergies can present with a wide clinical spectrum ranging from oral allergy syndrome to anaphylaxis. Although rare, seed allergies should be considered due to their potential for severe anaphylactic reactions. The Cucurbitaceae family, which includes pumpkins and related species, ranks among the most common plant families used as human food. Patients with pumpkin seed allergy may develop sensitization to other edible seeds such as sesame, sunflower, flaxseed, and poppy seed. Furthermore, Cucurbitaceae species are associated with clinical cross-reactivity with other fruits including cucumber, melon, and watermelon.

Conclusion

In seed allergies, detailed patient history is essential to identify potential cross-reactivities. Comprehensive allergy testing panels should routinely include common edible seeds such as sesame, sunflower, pumpkin, flaxseed, and poppy seeds to enable a holistic approach to diagnosis and management.