Alpha-gal syndrome misdiagnosed as chronic spontaneous urticaria in a pediatric patient.

A report describes a case of a patient who started to develop wheals every couple of weeks at the age of 5. After two years of evolution, a first diagnostic workup was unable to identify a clear trigger of the hives. Skin prick testing for inhalation allergens was negative for different pollen, house dust mites, mold, and animal dander. Laboratory investigations revealed total IgE levels (22 IU/mL) and tryptase (4.7 ng/mL) to be within normal ranges, adequate thyroid function, no anti-thyroid peroxidase (TPO) antibodies, and no signs of infection with parasites or Helicobacter pylori. The patient received discharged with the working hypothesis of chronic spontaneous urticaria and received antihistamines as symptomatic treatment.

Six months later, the boy again presented with generalized urticaria, edema, dyspnoea, and vomiting. He received an epinephrine injector that resolved the symptoms. His lab investigations showed elevated Tryptase levels. Several hours before these symptoms, earlier that same day, he reported eating three Cervelat sausages (typical Swiss sausages containing beef and pork meat) as well as jelly beans containing gelatine, which had already shown some wheals before going to bed and then other symptoms developed in the middle of the night, suggesting a delayed allergic reaction to meat. The mother also reported that the patient had suffered several tick bites before and that the only meat he eats regularly is the Cervelat sausage. His specific IgEs for alpha-gal were elevated with 21.2 kUA/L, levels for gelatin (bovine) were < 0.1kU/L, whereas tryptase levels had normalized after the reaction (6 ng/mL), confirming the suspicion of a delayed-appearing IgE-mediated allergic reaction to meat. He received emergency medicine, advice for avoiding red meat and other gelatine-containing foods, and a treatment plan. 

The avoidance diet caused the resolution of all symptoms, including wheals, together with the laboratory results, which reconfirmed the diagnosis of alpha-gal syndrome. Over the last three years, the family reported two accidents, one after eating a red meat-containing sausage at a barbecue (BBQ) and one after ingesting marshmallows. Both accidents happened at school, and the patient only presented with hives. 

Enders FB, Elkuch M, Wörner A, et al. Alpha-gal syndrome initially misdiagnosed as chronic spontaneous urticaria in a pediatric patient: a case report and review of the literature. J Med Case Reports.2023; 17. https://doi.org/10.1186/s13256-022-03718-8