Oral allergy syndrome induced by chestnut (Castanea sativa)

Background: Oral allergy syndrome is a distinctive type of allergy to food resulting from direct contact between food and the oral mucosa. Normally, it affects patients who are allergic to pollens. It can be challenged by testing for hypersensitivity to fresh fruit or vegetables in well-known associations. Oral allergy syndrome rarely occurs in patients with other types of allergies, or to food not associated with pollens. Only occasionally does chestnut cause hypersensitivity. There are only a few reported cases, depending on cross-reactivity in previously latex-hypersensitive patients. Oral allergy syndrome to chestnut in a patient with respiratory allergy to Dermatophagoides is therefore unusual and worth reporting. Objectives: To describe the clinical features and their differences from previously reported cases and to analyze the techniques and methodologic problems related to in vivo and in vitro diagnosis. Methods: Case report. Skin tests with commercial and freshly made extracts and by the prick-by-prick method. Challenge test. Specific IgE antibody assay. Prausnitz-Kustner reaction. Results: The challenge with fresh food confirmed an oral allergy syndrome to chestnut. Clear symptoms of rhinoconjunctivitis and asthma set in as well. Skin tests with several commercial extracts and the prick-by-prick test were negative and so was specific IgE assay in serum by PAST and other immunoenzymatic methods. Skin prick test with a freshly prepared extract of fresh chestnut and the passive transfer reaction were positive. Conclusions: The case of oral allergy syndrome to chestnut reported here appears to be a manifestation of immediate IgE-dependent hypersensitivity.