Papular urticaria.

Papular urticaria is a common and often distressing childhood disorder manifested by chronic or recurrent papules caused by a hypersensitivity reaction to the bites of mosquitoes, fleas, bedbugs, and other insects. Individual papules may surround a wheal and often have a central punctum. The histopathology of papular urticaria consists of mild subepidermal edema, extravasation of erythrocytes, interstitial eosinophils, and exocytosis of lymphocytes. Papular urticaria may represent a clinical challenge, particularly during spring and summer months.