A 26-year-old man presents to the clinic 2 weeks after being seen for an episode of urticaria, swelling of the lips, eyes, and throat, shortness of breath with wheezing, and diarrhea that began 15 minutes after being stung by an unidentified insect. He was treated with intramuscular epinephrine, systemic corticosteroids, and antihistamines, and his symptoms improved over 1 to 2 hours. He was sent home with a prescription for self-injectable epinephrine and instructions on its use. He is otherwise healthy. He takes no medications and has no medication allergies.

Which of the following is the most appropriate next step for this patient?

A. Patch testing for Hymenoptera venoms
B. No further evaluation is needed
C. Sting challenge with Hymenoptera venoms
D. Both skin and serum immunoglobulin E testing for Hymenoptera venoms

 

Rationale:

The correct answer is both skin and serum immunoglobulin E testing for Hymenoptera venoms. This patient has a history consistent with anaphylaxis to an insect sting from Hymenoptera, the most common of which are yellow jacket, hornet, wasp, and honeybee. Further evaluation is recommended because this patient may benefit from treatment with allergen immunotherapy, which may substantially reduce the risk of future anaphylaxis to such stings. Recent evidence suggests that both skin and serum immunoglobulin E testing will yield the highest sensitivity for identifying allergies to these insects. A sting challenge (insertion of stinger with venom sac into the patient’s skin) is the criterion standard for diagnosis of stinging insect allergy, but it involves substantial risk and is usually limited to a research setting. Patch testing for Hymenoptera is unlikely of any benefit because this type of testing assesses for a type IV, cell-mediated mechanism, and the mechanism for Hymenoptera anaphylaxis is type I, immunoglobulin E–mediated.

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