patch testing

Indications

• investigation of type IV hypersensitivity reactions leading to contact dermatitis

Clinical significance

• patch testing is distinguished from allergen skin testing (immediate wheal or flare reaction of allergen-specific IgE) used for assessment of respiratory allergies to pollens & molds.
• most molecules that cause type IV hypersenstivity reactions are small organic molecules which can penetrate skin barriers
  • responses involve haptenation of endogenous dermal proteins & elicitation of an immunological response.
• in addition to small organic molecules, the house dust mite can also cause a type IV hypersensitivity (as well as allergen- specific IgE response).

Procedure

• tests are read at 96 hours.

More general terms

• skin testing

More specific terms

• photopatch testing

Additional terms

• contact dermatitis (exogenous eczema)