The patient was a 15 year old male who was referred to the allergy clinic for suspected anaphylaxis to avocado. In the summer of 2010, the patient was eating guacamole dip with chips and within a half an hour of eating the guacamole, he developed coughing, wheezing, nasal stuffiness, generalized urticaria and periorbital edema. He did not experience any nausea, vomiting, diarrhea, syncope or loss of consciousness. The patient had eaten the same brand of chips multiple times in the past, but did not remember if he had consumed avocado before.
A family member provided the patient with an antihistamine but the symptoms didn't improve so he went to the emergency department. At the emergency department, intravenous antihistamine and steroid were administered. Within a few hours, the symptoms resolved and the patient was discharged with a script for oral steroid as well as an EpiPen®.
The diet of the patient was unrestricted. He had been exposed to latex in the form of balloons multiple times in the past without a reaction. In addition, his diet included other foods that are often included in latex-fruit syndrome (kiwi, banana, potato) [4]. It was unclear if he had previously ingested chestnut.
The patient's past medical history revealed resolved "eczema" to the neck, posterior popliteal and antecubital fossae. There was no history of asthma or allergic rhinitis. The patient reported a history of cold induced hives. The family history included a mother with asthma, an older brother with "environmental allergies" and asthma, and a sister with "environmental allergies" and asthma.
A complete physical examination was unremarkable. The patient underwent epicutaneous testing via prick technique for fresh avocado, commercial avocado extract, fresh and commercial chestnut, and guacamole dip. In addition, an ice cube test was done. Skin testing was positive to fresh avocado (10 mm) and commercial extract (5 mm) and borderline to the guacamole mix (3 mm). Testing to fresh and commercial chestnut was positive to fresh chestnut (10 mm) and commercial chestnut (6 mm). Histamine was 5 mm, and saline control was 2 mm. The ice cube test revealed faint, transient localized urticaria. A latex use test (both finger and full glove) was negative. ImmunoCAP to avocado was positive at 0.9 KUA/L.
An oral challenge to chestnut will be considered, should the family be willing, at a later date, to confirm whether a clinical allergy to chestnut exists.