Anaphylaxis to duck and goose eggs with preserved tolerance to hen's eggs: A case report.

BACKGROUND: Selective allergy to eggs from specific avian species, while maintaining tolerance to hen's eggs, is rare and may present diagnostic challenges. CASE REPORT: We report the case of a 75-year-old woman with no history of atopic disease who experienced episodes of anaphylaxis after consuming duck and goose eggs, while tolerating hen's eggs. Skin prick tests with commercial hen's egg extracts were negative. Serum testing revealed very low total IgE levels (5 kU/L) and low specific IgE to ovomucoid (Gal d 1), with negative results for other egg proteins. Prick-to-prick testing showed positive reactions to raw duck and goose egg white, whereas results were negative for cooked duck and goose eggs and for both raw and cooked hen's and quail eggs. An oral food challenge confirmed tolerance to hen's eggs. CONCLUSION: This case highlights a rare presentation of selective allergy to eggs from the Anseriformes order with preserved tolerance to hen's eggs. Comprehensive allergy evaluation - including skin testing, specific IgE measurement, and oral food challenges - may be essential to identify selective sensitizations and to provide appropriate dietary recommendations.