Patient with peanut allergy with NEGATIVE cutaneous and IN VITRO TESTS, confirmed by ORAL CONTROLLED food challenge

Background: The peanut allergy and dry fruit allergy in general is not very frequent in our country and its prevalence is ignored, being this more important in developed countries as United States where an increment is reported in the last years (1). Their manifestations generally debut in the childhood what differs of the case that will be presented next, where the symptoms began to the 50 years of age. 

Objective: To present the case of a 58 years-old woman with history of two previous episodes of angioedema caused by peanut consumption with negative cutaneous and in vitro tests whose clinical condition was confirmed by means of a oral controlled food challenge with peanut and whose has like comorbidity aspirin allergy.

Method: For the patient's diagnostic approach was conducted a skin prick test with food extracts that included the peanut extract, we also did a prick by prick test with peanut. Specific IgE for peanut was requested, and finally we carry out a controlled oral food challenge.

For the study of the reactions to the NSAID a nasal challenge with aspirin and an oral controlled challenge with meloxicam was carried out to offer the patient an anti-inflammatory option in the event of needing it.

Results:  the skin prick test, prick by prick test with peanut and specific IgE in vitro test for peanut allergy was all negative, the controlled oral food challenge with peanut caused an episode of urticaria and angioedema, with an accumulated dose of 9 grams of peanut. The controlled nasal aspirin challenge was positive and in the controlled drug challenge with meloxicam the patient tolerated a total dose of 15 mg of medication without presenting adverse reactions. 

Conclusion: The most interesting fact in this case is that although it has been described a sensibility and negative predictive values for peanut prick test over 95% (2) and a lower but not worthless diagnostic accuracy for in vitro test, we suggest that according with our patient, if there is a positive causal relationship in the medical interview a controlled oral food challenge must be carried out as the gold standard for food allergy diagnosis.

References

1.      Scott H. Sicherer, MD,a Anne Muņoz-Furlong, BA,c James H. Godbold, PhD,b and Hugh A. Sampson, MDa . US prevalence of self-reported peanut, tree nut, and sesame allergy: 11-year follow-up JACI 2010; 125(6): 1322

2.      Saleh Al-Muhsen, Ann E. Clarke, Rhoda S. Kagan. Peanut allergy: an overview. CMAJ 2003; 168(10): 1529