Anaphylaxis after eating Italian pizza containing buckwheat as the hidden food allergen

A 20-year-old woman developed anaphylaxis after eating pizza on 4 different occasions in 2 restaurants. Both restaurants made their pizza dough with a mixture of wheat and buckwheat flours. A prick-to-prick test with buckwheat flour was positive. Skin prick tests and specific immunoglobulin E responses to soybean and peanut were weakly positive while the response to buckwheat was negative. We ruled out a pathogenic role for peanut and soybean because the patient usually eats both with no signs of allergic reaction. Double-blind, placebo-controlled food challenges with buckwheat flour were positive after the administration of a cumulative dose of 2.3 g of the culprit flour. To our knowledge, our report describes the first case of anaphylaxis after intake of buckwheat flour as the hidden allergen in pizza dough.