Allergic contact dermatitis
Last Updated: 2022-02-04
Contact dermatitis, contact allergy
Type IV allergy mediated by sensitised T lymphocytes on contact exposure to triggering allergens. In some cases, an airborne contact may be causative.
- Prevalence in the population between 5-30% (depending on source)
- Women > men
- Acute allergic contact dermatitis
- Chronic allergic contact dermatitis
Within 1-2 days, a erythematous plaque forms at the site of the contact allergen, which is initially limited to the actual site of contact. Afterwards, satellite lesions form and the border is blurred. The plaque is infiltrated and vesicles are formed. Depending on the intensity, this effect can also be dramatic with large-scale blisters, erosions at the opening, crusts and superinfection.
Because this is a T cell reaction, which can persist for some time without antigen replenishment, removal of the contact allergen is not immediately diagnostic. On the contrary, the reaction may continue (see also drug exanthema) before it improves (crescendo).
Since we observe a spreading with persistent contact, the clinical picture resembles a generalised disease with time, but the focus still remains on the contact site.
- Epicutaneous testing
Depends on the allergens in question as well as the scattering patterns.
In some cases, performing a ROAT (repeated open application test) can be helpful.
Analysis of ingredients and avoidance of sensitive preparations (wool wax) is useful.
If allergen exposure persists and/or additional eczema-maintaining factors such as irritant influences occur, the eczema may become chronic.
- Exposure prophylaxis
- Topical therapy
For acute eczema, a water-based cream is used, while for subacute or chronic eczema, a greasy ointment base is targeted. The principle of "wet on wet, dry (or greasy) on dry" applies.
Rhagades can be closed with medical glue.
- Remoisturising local therapy
- Clobetasone cream/ointment
- Mometasone fuorate cream/ solution/ ointment
- Clobetasol foam (only if not erosive, as it burns) cream/ ointment
- UVB narrowband, bath PUVA
Systemic therapy (only necessary in individual cases)
- Prednisolone p.o. 25-100 mg 1x tgl. for a few days to weeks, no long-term therapy option
- Alitretinoin 10-30mg, in contrast to acitretin, thyroid function can be affected as it binds to RAR and RXR, therefore determination of TSH beforehand along with lipids/cholesterol levels fasting
- Methotrexate 10mg-25mg s.c. per week
- Cyclosporine (no long-term option)
- Schnuch A, Uter W, Reich K. Allergic Contact Dermatitis and Atopic Eczema. Handbook of Atopic Eczema: Springer Science + Business Media:178-201.
- Saint-Mezard P, Rosieres A, Krasteva M, et al. Allergic contact dermatitis. Eur J Dermatol 2004;14:284-95.
- Gober MD, Gaspari AA. Allergic contact dermatitis. Curr Dir Autoimmun 2008;10:1-26.
- Molin S, Vollmer S, Weiss EH, Ruzicka T, Prinz JC. Filaggrin mutations may confer susceptibility to chronic hand eczema characterized by combined allergic and irritant contact dermatitis. British Journal of Dermatology 2009;161:801-7.
- Usatine RP, Riojas M. Diagnosis and management of contact dermatitis. Am Fam Physician 2010;82:249-55.