Allergic contact dermatitis can occur at any age. But it is uncommon in young children and in individuals older than 70 years of age.
How Does Allergic Contact Dermatitis Occur?
Allergic contact dermatitis is a classic delayed cell mediated type of allergic reaction. When a person comes in contact with an allergen, for example poison ivy resin, the Langerhans cells of the epidermis takes up the antigen, process it and present it to T lymphocytes in the lymph nodes. T lymphocytes, thus activated, proliferate and become capable of producing what are called cytokines in response to the specific antigens. This whole process of sensitization takes 7-21 days, though some weak antigens can take many months to get sensitized.
When the skin is exposed to the same antigen later on, within a period of 6 hours to 24 hours (sometimes earlier), the Langerhans cells present them to the activated T lymphocytes in the lymph nodes and the blood stream, which in turn, release the cytokines, resulting in inflammatory responses in the skin.
In contrast to contact irritant dermatitis, as the skin is sensitized throughout, the reaction can occur anywhere on the body in this type of contact dermatitis.
What are the Signs and Symptoms of Allergic Contact Dermatitis?
Intense itching and burning sensations precede and accompany the eruptions in acute ACD (allergic contact dermatitis). In severe attack, fever and body pain will be present.
The itchy skin rashes of allergic contact dermatitis depends upon the severity, site of involvement and duration of exposure to the allergen.
- In acute stage, the skin turns red and edematous (swollen) and is peppered with fluid filled vesicles. In severe reactions, as in allergic contact dermatitis to poison ivy or hair dye, large bullae and erosions are present.
- In sub acute stage, there are patches of red skin showing dry scales, erosions, and small pointed or round bumps.
- In the chronic stage of allergic contact dermatitis, the skin becomes thickened, pigmented and the skin markings become prominent following incessant scratching and rubbing. The thickened skin can show painful fissures and crusting as well.
Diagnosis of Allergic Contact Dermatitis
Patch testing with the suspected allergens on the back of the trunk can pinpoint the culprit allergen in most cases.
The Top Ten Contact Allergens
- Nickel sulphate, in metals, jewelry, watch straps, buttons, hooks.
- Neomycin sulphate, in creams and ointments.
- Balsam of Peru, topical medications.
- Fragrances, in cosmetics.
- Thimerosal, in antiseptics.
- Sodium gold thiosulphate, in medications.
- Formaldehyde, in disinfectants, plastics.
- Quaternium 15, in disinfectants.
- Cobalt chloride, in cement, industrial oils, eyeshades.
- Para phenylene diamine, in dyes.
Treatment of Allergic Contact Dermatitis
- Identification and removal of the allergen.
- Acute skin rashes: Wet soaks, followed by
- Topical steroids(Class I to III).
- Larger blisters can be drained, but the roof should be preserved.
- A 1-2 weeks’ course of systemic steroids may be required in severe, generalized allergic contact dermatitis.
- Steroid sparing treatments with topical calcineurin inhibitors like tacrolimus, phototherapy etc are useful in chronic allergic contact dermatitis.
Reference
- Contact Dermatitis, in Rook’s Textbook of Dermatology, 7th Edition, 2004
- Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology, Fifth Ed, 2005
Disclaimer
The information given in this article is for educational purpose only so that patients are aware of the options available. No diagnosis should be made or treatment undertaken without first consulting your doctor. If you do so, the author or suite101 will not be responsible for any consequences. The images provided are for illustration purpose only.
 |
 |
 |
