Textbook of Contact Dermatitis (2nd ed.)

10. 1. 1. 1 The Purpose of Patch Testing Patch testing is a well-established method of diagnosing allergic contact dermatitis, a delayed type of hypersensitivity (type IV reaction). Patients with a history and clinical picture of contact dermatitis are reexposed to the suspected allergens under controlled conditions to verify the diagnosis. Besides testing patients with hand, arm, face or leg eczema (stasis dermatitis), testing of other types of eczema (atopic, seborrhoeic dermatitis, nummular e