Beware of the caterpillar: Anaphylaxis to the spotted tussock moth caterpillar, Lophocampa maculata.

We present a case report of a 5-year-old boy with presumed anaphylaxis to the caterpillar, Lophocampa maculata, manifesting as the acute development of diffuse urticaria and progressive dyspnea. This reaction required prompt treatment with antihistamines and a bronchodilator. Allergen scratch testing with a homogenized caterpillar extract suggests that immunoglobulin E-mediated type I hypersensitivity as the pathophysiological mechanism responsible for the boy's anaphylaxis.