Reference Work Entry

Encyclopedia of Molecular Mechanisms of Disease

pp 412-413

Contact Allergy

  • Andrea CavaniAffiliated withLaboratory of Immunology and Allergology, Istituto Dermopatico dell’Immacolata, IDI-IRCCS
  • , Giampiero GirolomoniAffiliated withDepartment of Biomedical and Surgical Sciences, Section of Dermatology, University of Verona


Allergic contact dermatitis; Contact hypersensitivity

Definition and Characteristics

Itchy skin reaction with erythema, edema and vesicles occurring at the site of penetration of chemicals in pre-sensitized individuals. In the chronic phase, increased epidermal thickness with scales and painful fissures are frequent.


Widely common disease in both professional and extraprofessional settings. Prevalence in general population varies dramatically depending on the source considered. It has been reported that 2–15% of individuals residing in industrialized countries are skin sensitized at least to one substance, but the general assumption is that prevalence is greatly underestimated.

Molecular and Systemic Pathophysiology

Contact allergy is the consequence of an unbalanced T cell immune reaction against small chemicals, named haptens, contacting the skin. In the sensitization process, the hapte ...

This is an excerpt from the content