Multiple shifting phenotypes with cow's milk: From eosinophilic esophagitis to immediate hypersensitivity and back again

Cow's milk allergy (CMA) is one of the most common food allergies among children.1 Although this allergy is outgrown in 75% of children by teenage years,1 oral immunotherapy (OIT) has been studied in the subset of patients who are unlikely to outgrow it. OIT involves administering incremental doses of cow's milk (CM) protein to a maintenance dose, with the goal of developing tolerance to CM protein.2 Eosinophilic esophagitis (EoE) is a chronic immune-mediated disease that has emerged over the last 2 decades.3 Management of EoE involves either medication (proton pump inhibitor or swallowed topical corticosteroid) or dietary elimination of possible food triggers, the most common of which is CM.3 CM elimination can induce histologic remission in up to 64% of patients with EoE.4 Although successful, one of the theoretical risks is development of IgE-mediated allergy secondary to CM avoidance. Recently, cases have been reported of IgE-mediated allergy to CM after elimination for EoE treatment.5,6 Although OIT is a promising treatment for food allergy, an association between OIT and the development of EoE has been suggested, estimated at 2.7% (range: 0.99% to 5.33%).7 EoE is therefore considered an absolute contraindication to the continuation or initiation of OIT.7 We describe a 4-year-old girl with a history of multiple food allergies (peanut, tree nut, sunflower seed, fish), atopic dermatitis, and seasonal allergic rhinitis.