Omalizumab for severe IgE-mediated food allergy and severe asthma after pediatric liver transplantation: a case report.

Transplant-associated allergy represents a clinically relevant phenomenon described after hematopoietic stem cell transplantation and, particularly in pediatric patients, after solid organ transplantation. Liver transplant (LT) in the pediatric population is associated with de novo IgE-mediated allergy, including asthma, atopic dermatitis, and severe food allergies. De novo post-transplant food allergy (dnPTFA) is a condition with multiple risk factors involved, including young recipient age, female sex, personal or donor history of atopy, calcineurin inhibitors, and Epstein-Barr virus infection. These factors likely converge to promote post-transplant immune dysregulation through both passive and active mechanisms driven by calcineurin inhibitor (CNI)-induced Th2 skewing and viral immune modulation. This paper presents a narrative review of dnPTFA and a clinical case of a 15-year-old boy who underwent LT at 28 days of age due to neonatal acute liver failure. The patient subsequently developed severe asthma and multiple dnPTFAs with recurrent anaphylaxis, despite immunosuppression being maintained at low target levels throughout post-transplant follow-up due to normal graft function. Because of persistent life-threatening reactions, allergic asthma, and marked food selectivity compromising growth, off-label treatment with omalizumab was initiated at 10 years of age. Following treatment with omalizumab, the patient achieved excellent asthma control, discontinued background therapy, and resumed a less restricted diet. Liver graft function has remained stable, with no graft-related adverse events over more than 5 years of follow-up, supporting the long-term safety and effectiveness of this approach.