A. Antico, M. Arisi, G. Lima

Background. Paediatric age, active eczema and high number of allergens tested in poly-sensitized patients have been pinpointed as possible risk factors of systemic reactions by skin prick testing. As far as atopic eczema concerns, the higher penetration of the allergens into the skin because of the scraping or micro-injuries is an intuitive rationalization. Purpose of the present study is to provide documentary evidence that adverse reactions elicited by anomalous absorption of allergens can occur also in adult patients with apparently normal skin.
Methods. Report of some exemplifying clinical and experimental observations. Measuring the inoculum volume into impaired skin and its variability in relation to the variation of the chemical-physical characteristic of the solutions used for the tests by means of a method of direct assay based on the use of a gamma-camera. Results. Localized impairments of the skin permeability can cause a significant increase in inoculum volume by prick-test. Critical amounts of allergens can be introduced into the skin because of the possibility of direct absorption, also without pricking, of allergy diagnostic solutions. The greater water content of the solutions used for prick-testing can significantly increase the inoculum volume. Conclusions. This study adds clinical and experimental evidences that localized impairments of permeability can occur in adult patients with apparently normal skin. Special precautions should be taken when a change of the drops' normal shape and cohesion is seen, because allergy prick-testing in such areas is potentially associated with increased risk of large local or systemic reactions.