Anaphylaxis after home-made quinoa dinner: hold the mustard

Description

Food is the most common cause of anaphylaxis.¹ Very few cases of mustard seed-induced anaphylaxis have been reported. We present a case of mustard seed anaphylaxis. A 29-year-old man presented to our department for evaluation of anaphylaxis. He had an episode of facial flushing and angio-oedema (figure 1), lower extremity urticaria (figure 2), chest tightness and vomiting within 30 min of eating a prepared quinoa dish at home. He did not seek medical attention and his symptoms resolved within hours of self-administration of loratadine and diphenhydramine. He had no relevant medical history of previous adverse reactions to foods. On further questioning, the patient revealed the ingredients in the quinoa dish: chicken, rice, avocado, ginger, onion, potatoes, tomato, nutmeg, yeast, soy, wheat, black pepper, thyme and mustard seed. He had previously tolerated quinoa without adverse reactions. However, in this latest preparation, the two last ingredients were obtained from a new brand. His physical examination was unremarkable. Percutaneous skin testing was positive to soy and prick-prick testing to mustard seed. He was instructed on avoidance measures including food label reading and prescribed epinephrine auto injector. This case demonstrates the importance of an adequate clinical history and detailed content of ingredients.

Learning points.

• Conjunction of careful history and skin testing allowed the identification of the aetiology and establishment of diagnosis of this anaphylactic reaction secondary to mustard seed.

• Despite the widespread use of mustard seed for culinary purposes, food IgE-mediated mustard seed allergy has been considered a rare cause of food allergy, mainly described in Spain, where the biggest case series have been reported.^{2 3}

• Mustard seed is frequently used in mustard sauce and seasonings. This may make avoidance challenging for patients.

Figure 1.

Facial flushing and angio-oedema (A). Patient's face without symptoms (B).

Figure 2.

Lower extremity with generalised urticaria (A) and without urticaria (B).