Bean bag allergy revisited: a case of allergy to inhaled soybean dust.

BACKGROUND

Soybean is a common food allergen. It can cause Type 1 allergy (IgE-mediated) symptoms from its ingestion, as well as from inhalation of its dust.

OBJECTIVE

To report a case of allergy in a child from the inhalation of soybean dust from a bean bag and the course of this allergy over time.

METHODS

Case report; routine skin testing and laboratory tests; bean bag challenge studies; special studies with saline extracts of the bean bag soybeans.

RESULTS

A 6-year-old boy with a 1-year history of allergic rhinitis noted symptoms of urticaria, eyelid angioedema, and mild respiratory distress while at school playing with a bean bag containing soybeans. Skin tests revealed positive reactions to commercial soybean extract and bean bag soybean extracts. Bean bag challenge was also positive. The patient's serum was able to transfer this sensitivity by the Prausnitz-Küstner (P-K) reaction. RAST and polystyrene tube radioimmunoassay techniques, however, did not detect specific IgE to soybean allergens. During follow-up, the patient developed allergy symptoms with ingestion of other beans. This latter allergy lasted for only 2 years, but the bean bag allergy was still present 4 years later (bean bag challenge). The patient returned at age 19 for recurrence of his allergic rhinitis and de novo asthma. Repeat bean bag challenge at age 24 was negative.

CONCLUSIONS

To the best of our knowledge, this is the first reported childhood case of IgE-mediated allergy from soybean dust during play with a bean bag containing dry soybeans. Over time, despite the loss of this sensitivity, he developed asthma, another IgE-mediated illness.