Clinical Allergy Tips
Edited by Stuart A. Friedman, MD
Editor’s Note: Clinicians at the Baylor College of Medicine/Texas Children’s Hospital group tell us about an
approach to a recent case of urticaria and angioedema initially thought to be due to pizza. Pizza is a world-popular
dish made with flat baked bread, tomatoes, mozzarella cheese and a variety of toppings. The 2006 Practice
Parameters of the Joint Task Force of the American Academy of Allergy Asthma and Immunology (AAAAI) and
American College of Allergy Asthma and Immunology (ACAAI) cite 95% accuracy for percutaneous skin tests in
ruling out IgE-mediated reactions; thus the clinicians proceeded to an ingestion challenge.
Madhu B. Narra, MD, MS
Chief Fellow, Section of Immunology, Allergy &
Rheumatology, Department of Medicine
Baylor College of Medicine, Houston, Texas USA
Co-authors: Carla M. Davis, MD; William T. Shearer
Baylor College of Medicine; Texas Children’s Hospital
Presumed pizza allergy disproven
18 September 2009
Within 5 minutes of eating a slice of pizza at a restaurant, a 14-year-old boy suddenly developed flushing
and hives on his face accompanied by swollen lips and uvula. The boy’s mother, who was a physician,
immediately administered oral diphenhydramine and took him to the emergency room. Evaluation did
not reveal wheezing, coughing, vomiting or a drop in blood pressure; thus he was not treated with
epinephrine. He stopped eating pizza and tomatoes for several months after the episode. He saw us in
the clinic as it was difficult to avoid a food like pizza. He had no past history of food allergies or
aeroallergen sensitivity and his Immunoglobulin E (IgE) level was normal.
Since there were multiple ingredients in the pizza, we felt that it was inappropriate to avoid the entire
pizza instead of the specific component that caused the reaction. We decided to pursue skin testing to
foods and, if necessary, oral food challenge. Immediate hypersensitivity skin testing (IHST) was negative
to fresh tomato, beef, pork, basil, oregano, garlic and onion. The sauce on the pizza was made from
tomatoes, citric acid and salt. Oral food challenge with 10 grams of tomato was well tolerated and
reintroduced into his diet without any reactions. In the next visit, the patient was asked to bring the
same type and brand of pizza slice that was associated with past symptoms. IHST was performed to the
ingredients of the pizza (ham, sausage, cheese, and wheat crust directly from the pizza); all were
negative. With our clinical suspicion of allergy to pizza being low at this point, we performed an oral
food challenge with the pizza, and the boy was able to eat the entire slice without any immediate or late
symptoms. The boy and his family were thrilled, now that he could eat pizza again, and his quality of life
improved significantly. The cause of the patient’s initial reaction remains unknown and has not
recurred.
WAO Clinical Allergy Tips
Copyright 2009 World Allergy Organization
About 20 – 25 % of people think they have food allergy because of some symptoms after eating a food.
In reality less than a third of these individuals (6-8% of the general pediatric population and 3-4% of the
general adult population) are truly allergic to food.1 This case demonstrates that our patient did not
have a true allergy to pizza or any of its components. A history of allergy to foods with multiple
ingredients should be further investigated by the allergist with IHST directed at specific food
components. The best skin testing method to test for allergy to fresh fruits and vegetables is the "prickprick" method, where the fresh food is pricked followed by pricking the patient's skin.2 If necessary, food
challenge should be done to help avoid unnecessary food restrictions that can significantly affect quality
of life. This decision can be guided by the importance of the food to the patient because of its nutritional
value, ubiquitous presence in the diet, and the patient’s and family’s preferences.3
References
1. Sampson HA. Update on food allergy. J Allergy Clin Immunol. 2004; 113: 805-819.
2. Chapman JA, Bernstein IL, Lee RI, Oppenhemier J, eds. Food allergy. A practice parameter. Ann Allergy
Asthma Immunol 2006; 96 (3 suppl 2): S1-S68.
3. Nowak-Wegrzyn A, Assa'ad AH, Bahna SL, Bock SA, Sicherer SH, Teuber SS. Work Group report: oral
food challenge testing. J Allergy Clin Immunol. 2009; 123 (6 Suppl): S365-383.
WAO Clinical Allergy Tips
Copyright 2009 World Allergy Organization