Epicutaneous tests are used to diagnose allergic contact dermatitis and to identify specific allergens that may cause the condition.
Indications
- Persistent skin rash suspected to be contact allergy
- Any chronic skin inflammation, especially if it affects the hands, feet, eyelids, or face
- Eczematous skin inflammation in individuals working in high-risk professions for contact dermatitis (healthcare workers, cosmetologists, machinists, or those working with rubber and plastic)
- Skin inflammation of unknown origin
- Worsening of previously stable skin inflammation
- Differentiating allergic contact dermatitis from irritant, atopic, seborrheic, and stasis dermatitis, nummular and asteatotic eczema, and psoriasis
Contraindications
- Rash on the back
- Heavily tanned skin
- Pregnancy and breastfeeding (tests have not been found to harm the fetus or mother, but are generally postponed as a precaution)
- Treatment with systemic corticosteroids and cytostatics. Treatment with antihistamines, ibuprofen, and biological drugs such as adalimumab, etanercept, ustekinumab, and infliximab can continue.
Preparation for the Test
Certain factors can influence the test results, so it is important to note the following:
- 2-4 weeks must have passed since the exacerbation of skin inflammation in the test area
- At least 4 weeks must have passed since intensive tanning
- 2 weeks must have passed since the use of corticosteroid ointments in the test area
- It is recommended to take a shower on the morning of the test day
- Do not use skin care products on the test area on the morning of the test day
- If the back is hairy, shave the upper back 2 days before the test
Conducting the Test
You will need to visit the clinic three times in a week (Monday, Wednesday, and Friday). On the first visit, allergens will be applied to your upper back using patches, which will remain in place for 48 hours. For patch removal and assessment of the epicutaneous test results, you will visit the nurse for the second visit. On the third visit, the doctor will make the final evaluation of the test results.
During the five-day testing period:
- Avoid activities that cause sweating (exercise, sauna, heavy physical work), which can cause the patches to come off
- Avoid tanning and light therapy on the back
- You may experience moderate itching and discomfort in the test area. If the itching is very severe, you can remove the patch yourself. Ensure the patches are properly adhered to the skin. If the edges of the patches lift, secure them with additional tape.
Possible Side Effects
Epicutaneous tests are generally safe and do not cause serious allergic reactions. Some side effects may occur:
- Hypersensitivity to the patch or chamber material
- Skin irritation reaction
- Exacerbation of existing rash, known as “angry back syndrome” (a strongly positive result makes the skin hyperreactive, causing positive reactions in many other allergen areas that would otherwise be negative)
- Pressure effect from the chamber edges on the skin (subsides within 15-30 minutes after patch removal)
- Pigmentation or depigmentation
- Milia
- Prolonged persistence of a positive reaction
- Koebner phenomenon (in cases of psoriasis and lichen planus)
If any side effect worsens, contact your treating physician or visit the emergency department.