Differential Diagnosis for Oral Allergy Syndrome with Persistent Reactions

• Single most likely diagnosis:
  • Pollen-Food Allergy Syndrome (PFAS): This condition is characterized by oral allergy syndrome (OAS) symptoms that occur after consuming fresh fruits, vegetables, or nuts due to cross-reactivity with pollen allergens. The fact that reactions persist even with cooked foods suggests a more severe form of allergy, which could still be related to PFAS, especially if the individual has a high sensitivity to the specific allergen.
• Other Likely diagnoses:
  • IgE-mediated Food Allergy: A classic food allergy where the immune system overreacts to specific food proteins, leading to allergic reactions. The persistence of reactions to cooked foods suggests that the allergenic proteins are heat-stable.
  • Eosinophilic Esophagitis (EoE): A chronic inflammatory condition of the esophagus that can be triggered by food allergies, among other factors. Symptoms can include difficulty swallowing, food impaction, and heartburn, which might not be directly related to OAS but could be considered in the differential due to the involvement of food triggers.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Anaphylaxis: Although the question specifies oral allergy syndrome, any food allergy has the potential to cause anaphylaxis, a severe, life-threatening allergic reaction that requires immediate medical attention. It's crucial not to miss this diagnosis due to its high mortality rate if not promptly treated.
  • Food Protein-Induced Enterocolitis Syndrome (FPIES): A non-IgE-mediated food allergy that primarily affects infants but can occur in adults. It involves an inflammatory response to food proteins, leading to symptoms like vomiting, diarrhea, and abdominal pain. While less common, FPIES can lead to severe dehydration and should not be overlooked.
• Rare diagnoses:
  • Mastocytosis: A condition characterized by an accumulation of mast cells in one or more organs. It can lead to a variety of symptoms, including allergic-like reactions to foods. While rare, it could be considered in cases where typical allergy testing does not explain the severity or nature of the reactions.
  • Hereditary Angioedema (HAE): A rare genetic disorder that causes swelling of the face, extremities, and airways. It can be triggered by various factors, including stress, trauma, and certain foods. Although not directly related to OAS, its potential for severe, life-threatening airway obstruction makes it a diagnosis that should not be missed.