Certain endogenous substances, like
uric acid in
uremia, biliary salts in pregnancy or hepatobiliary
cirrhosis, or
histamine in atopic patients, can occasionally cause local reactions in the skin that result in prurigo lesions that are identical to the primary lesion of acute, subacute, or chronic prurigo. There are several types of prurigo that are more common in particular ethnic groups. The impression of itching can also be altered by emotional and environmental variables, which can lead to scratching and the development of a prurigo lesion. Itching can also be brought on by a number of exogenous variables, including
bacteria,
parasites, allergies applied topically or internally, and poisonous substances deposited beneath the skin. The primary source of itching is a mechanical reflex used to get rid of ectoparasites. In those who are sensitive, physical variables like
UV light can cause alterations in epidermal innervation, which can lead to prurigo sores and itching. == See also ==