The body a scratch on a piece of pimples to consider is due to urticaria, insect bite dermatitis and other causes. 1. urticaria: is a disease due to the skin mucous membranes appear limited edema reaction, usually in the external stimulus, make the skin appear pale white and accompanied by itching, can be manifested as a scratch on a piece of pimple symptoms. 2. Insect bite dermatitis: After insect bites, localized skin allergic reaction occurs, and there will be red spots with itching. When scratching, the reaction may expand, thus manifesting itself in the symptom of a pimple on the body when scratched. When the body appears uncomfortable symptoms, it is recommended to go to the hospital in time for examination and diagnosis, to clarify the cause of the disease, under the guidance of professional physicians for targeted treatment.