From anaphylaxis to eosinophilic esophagitis: when therapy leads to unintended immune shifts – a case report

Background Eosinophilic esophagitis (EoE) is a chronic inflammatory disease of the esophagus with symptoms of esophageal dysfunction. It is strongly associated with other atopic conditions in patients and has therefore been recognized as a late manifestation of the atopic march. Sensitization to foods and/or aeroallergens early in life may predispose some individuals to subsequent EoE development. Moreover, the disease was found to emerge as a potential side effect of oral immunotherapy (OIT). However, it remains unclear whether OIT induces or rather “unmasks” a pre-existing but subclinical disorder. Case Presentation We report a boy with IgE-mediated cow’s milk (CM) allergy, confirmed in infancy after anaphylaxis to yogurt, positive skin prick tests, and elevated CM-specific IgE. He tolerated baked milk following a supervised oral food challenge. From early childhood, he developed severe allergic asthma and rhinitis, refractory to standard therapy. Omalizumab (OMA) was initiated at 10 years of age with marked and sustained asthma control. While receiving anti-IgE treatment, at 13 years of age, the patient independently liberalized his diet and tolerated progressively less processed dairy products for 6–8 months without immediate hypersensitivity reactions. He subsequently developed recurrent vomiting and, two months later, experienced anaphylaxis after ingestion of a small amount of ice cream. Despite extensive evaluation during hospitalization, vomiting persisted and was associated with weight loss. Upper endoscopy revealed esophageal inflammation, with histological confirmation of EoE diagnosis. Treatment with proton pump inhibitor therapy, swallowed topical budesonide, and renewed strict CM elimination resulted in rapid clinical improvement, weight gain, reduction of peripheral eosinophilia, and histologic remission. Treatment with OMA was sustained. Conclusions The present case report illustrates that omalizumab can enable functional desensitization to CM in a child with a history of life-threatening reactions, but prolonged unsupervised consumption of CM under anti-IgE therapy may be associated with the onset of EoE. Awareness of this potential complication is crucial for clinicians managing children with severe food allergy and asthma on biological therapy.