Diagnosis

Patch testing is considered the gold standard for diagnosing contact allergy

Patch Test Mode of Action

The patch test procedure is an epicutaneous diagnostic provocation test using standardized haptens (“Patch Test Haptens”). Haptens are typically small, chemically reactive molecules with low molecular weight that, when bound to skin protein, are able to elicit an immune response. Patch testing is performed by applying haptens into small chambers mounted on tape (“Patch Test Units”) and placed onto the patient’s skin. In sensitized individuals this immune response results in an allergic contact eczema confined to the application area of the chamber on the patient’s skin (a positive patch test reaction).

Indications

diagnosis of Contact Allergy when Allergic Contact Dermatitis (ACD) resulting from type IV hypersensitivity is suspected. The indication is to test all patients in whom contact allergy is suspected or needs to be ruled out, regardless of age or anatomical site of dermatitis.

Indications also include conditions that may mimic a contact allergic reaction and needs to be ruleed out, such as:

• Erythema multiforme-like

• Lichen planus-like

• Psoriasis of the hands

• Granulomatous or lymphomatoid reactions

• Worsening of pre-existing dermatitis (stasis, atopic or seborrhoeic dermatitis)

• Mucous membrane reactions (conjunctivitis, stomatitis, vulvitis)

• Discoid (nummular) eczema

• Implant reactions

• Certain drug eruptions

Contraindications

Do not apply hapten on patients undergoing cortisone treatment or taking other medication altering the immune system such as immunosuppressive treatment.

Do not apply hapten on a patient with a known history of severe allergic reaction (local or systemic) to the hapten in question or on patients with severe or generalized active dermatitis.

Do not apply hapten on injured skin or on test area recently exposed to ultraviolet radiation (UV).

Do not apply hapten on patients with dermatitis on the upper back area aimed for the application of patch tests or on test sites recently treated with topical corticosteroids; wait at least 1 week after treatment.Pregnancy and lactation may be a conditional contraindication as there are no data on the safety of the test for the mother and child.