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Keywords:

  • atopy;
  • nut allergy;
  • poppy seed allergy

T he wide spectrum of clinical symptoms caused by food allergens includes potentially life-threatening immediate-type reactions. The association between sensitivity to diverse vegetables and sensitivity to different pollens is well known. Nevertheless, it is often difficult to find the causative allergen. Life-threatening allergic reactions are often caused by nuts. Moreover, nuts are often suspected due to their widespread availability and hidden occurrence in food preparations. Therefore, routine diagnosis considers those highly allergenic foods (e.g., hazelnuts, walnuts, and almonds) as well as pollen allergens.

We report on a 52-year-old patient who developed epigastric pain, angioedema, and respiratory distress a few minutes after eating a piece of poppy cake. It was the first such attack in his life and he required emergency care. He neither reported any similar previous adverse reaction to foods, nor did he suffer from any other serious disease. With regard to atopic symptoms, the presented patient did not complain of allergic rhinitis, asthma, or atopic eczema. The family history was also negative for atopy.

The diagnosis of poppy-seed allergy was confirmed by skin tests (prick) and specific IgE antibodies (RAST; specific IgE was 1.69 IU/ml, class 2). In the skin tests, an immediate type-I sensitivity to nuts (hazelnuts, walnuts, and almonds) without clinical relevance was detected as well. The patient did not report clinical symptoms of allergic rhinoconjunctivitis or oropharyngeal symptoms after consumption of special food products such as nuts and fruits. The prick tests were positive with raw and baked poppy seed, suggesting the thermostability of the relevant antigen.

Pollen-associated allergies to food preparations are more common in Europe than food allergies without any association with atopic symptoms, especially allergic rhinitis ( 1). Reports of allergic type-I sensitivity to poppy seed are rare. A member of the Papaveraceae family, the poppy flower grows as a weed in cereal fields and along country roads. Clinical symptoms in allergic patients may affect the skin, mucosa, and bronchial and gastrointestinal tract, as with other food allergens. According to the literature, severe reactions often occur, affecting mainly atopic patients ( 2–6).

Anaphylactic reactions after consumption of poppy cake were first reported by Wagner & Ring ( 2). The clinical symptoms ranged from itching around the mouth and lips, nausea, and dyspnea to anaphylactic reactions. The diagnosis was confirmed by prick test and RAST. As in our patient, positive skin reactions to several nut allergens were found, probably representing cross-reactivity between nuts and poppy seed. In 1997, Gamboa et al. ( 7) reported on an atopic patient who presented with a history of contact urticaria and angioedema after contact with poppy flowers.

Sensitization to poppy seed probably does not need special exposure. Reports of sensitizations already in childhood suggest that a genetic determination is important.

It is still unclear why in the reported cases poppy-seed allergy coincides with nut allergy. It is conceivable that in some cases sensitization to poppy allergens may occur by the more common nut allergens. On the other hand, at least in Germany, the use of poppy seed for cakes is common.

By this case report, we underline the necessity of an exact food anamnesis and emphasize the possibility of poppy-seed allergy, especially if one can find positive skin tests to nuts with lack of clinical relevance.

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