A SUBSTANTIAL body of evidence indicates that many cases of papular urticaria are related to insect bite sensitivity.* This opinion is based, in part, on the fact that the patients with papular urticaria give positive delayed (tuberculin type) skin test reactions to the intradermal injection of insect antigen. (Figs. 1, 2, and 3).
In an effort to determine the validity of this etiologic concept, we have examined a number of lesions of papular urticaria histologically and have compared these findings with those of positive urticarial and delayed tuberculin-type skin reactions to insect antigen, and with ordinary insect bites. These studies have shown a striking similarity of such lesions.
METHOD OF STUDY
Patients with papular urticaria were given intracutaneous injections of mosquito (Culex pipiens) flea, (Ctenocephalides felis), and bedbug (Cimex lectularius) antigens. These antigens were prepared after the method of Cherney and co-workers14; 0.1 cc. of 1: 5,000