D3.290 - Generalized Urticaria Induced from Prick-by-Prick Test in Food Allergy Diagnosis

Introduction: Evaluation of suspected food-induced anaphylaxis requires a careful assessment to identify the responsible allergen. Skin testing, alongside clinical history and specific IgE measurement, is a commonly used tool to support diagnosis and guide management, helping to confirm sensitization before considering an oral food challenge.

Case report: We report the case of young man 24 years old, who was presented for allergist evaluation 1 week after an anaphylaxis episode after eating few peanuts caramelized with sesame seeds, a snack which the patient consumed frequently. Few minutes after ingestion he was admitted to emergency due to generalized urticaria, face angioedema, difficulty breathing and hypotension.  3 weeks after the episode the patient performed sIgE extract and molecular which resulted negative for food allergens and aeroallergens. Total IgE was > 2500 IU/mL. Hemogram normal, biochemical within test normal. 1 month after the episode he presented to perform skin test, prick test with standard extracts for peanut was negative, for sesame sed not available. Pick by prick firstly for sesame (crushed seed with saline water 0.9%) and was negative after 20 minutes, Histamine positive 7-25 mm. peanut prick by prick was performed (crushed with saline water 0.9%) immediately 2 urticarial elements were appeared in lateral arm of test side (exposure with allergen was interrupted) and within 2 minutes generalized erythema with urticarial elements mostly in the scapular region.  A discrete 2 mm papule was present at prick zone. The patient was treated with Prednisolone 50 mg in 20 ml sol Nacl 0.9% IV and cetirizine 10 mg. No other systemic signed were developed. An adrenaline autoinjector was prescribed and strict avoidance of peanut allergen recommended.

Concussions: Although rare, systemic reactions can occur following prick-by-prick skin testing. Diagnosing food allergy remains challenging, and potential risks must be carefully considered during evaluation.