The multiple facets of cow's milk allergy.

Cow's milk allergy (CMA) is one of the most common food allergies in early childhood. CMA has varied presentations and multiple facets. A detailed clinical history is key for classification. In IgE-mediated CMA skin prick testing and serum specific IgE testing are useful in the diagnosis, but an oral food challenge (OFC) may still be necessary if there is doubt or to assess tolerance. Non-IgE-mediated CMA presentations include food protein-induced allergic proctocolitis (FPIAP), food protein-induced enterocolitis syndrome (FPIES), and eosinophilic esophagitis (EoE). The diagnosis of FPIAP and FPIES is based on the clinical history. An esophageal biopsy is required for the diagnosis of EoE. Atopy patch testing, IgG or IgG4 testing are not helpful in any CMA evaluation. Children with CMA (except those with FPIAP) are at risk for poor growth and a nutritional evaluation should be part of routine care. Extensively hydrolyzed formulas are the recommended first choice alternative formula for CMA. For IgE-mediated CMA, alternative approaches to traditional strict avoidance include oral immunotherapy (OIT) and omalizumab (both as monotherapy and as an adjunct to OIT). Multiple international guidelines have addressed evaluation and management of CMA providing key information, support and guidance for clinicians in daily practice.