Abstract
Background: Azuki bean is sometimes a nutritional alternative for those with soybean allergy. Although soybean and peanut are relatively common food allergens, azuki bean allergy has not previously been reported.
Case Report: A 3-year-old male was referred for investigation of suspected azuki bean allergy. He developed urticarial lesions within 30 min after eating an azuki bean product (manju, a sort of Japanese sweet), with a similar episode reported 1 year prior. The total serum immunoglobulin E (IgE) level was 677 IU/ml, with elevated specific IgE antibodies (ImmunoCAP) to soybean, peanut, kidney bean, and pea. Azuki bean specific IgE antibodies are not available, currently. The wheals produced by skin prick test (SPT) were boiled azuki bean without sugar 5 mm, yohkan (a typical Japanese sweet) 8 mm, sweetened azuki bean paste 7 mm, and soybean 4 mm. Double-blind placebo-controlled food challenge (DBPCFC) with azuki bean without sugar induced urticaria after 60 min, which resolved after oral antihistamine administration. He did not develop symptoms after ingestion of control.
Conclusions: This is the first reported case of immediate-type azuki bean allergy, diagnosed by SPT and DBPCFC. Further study such as immunoblotting is needed to elucidate the specific allergenic antigen.
