CONTACT DERMATITIS

Contact Dermatitis Can be subdivide into

1. ICD

2. ACD

3. Photocontact Dermatitis

4. Contact Urticaria

5. Reactions to pharmacological active agents

Definition ICD: is a condition caused by direct injury of the

skin An irritant is any agent capable to producing cell

damage in any individual ○ If applied for

sufficient time and In sufficient concentration

○ Immunologic processes are not involved ○ And dermatitis occurs w/o previous sensitization

Irritant cause damage by braking or removing the protection layers of the upper epidermisThey denature keratin

○ Remove lipids and ○ Alter the water holding capacity of the skin

Resulting in damage of the underlying living cells of the epidermis

The severity of dermatitis produced by an irritant depends on the type of: Exposure Vehicle and Individual propensity

Normal, dry , or thick skin is more resistant to irritants than moist, macerated or thin skin

ICD is induced by toxic substance and develops at: The site of contact with the injurious substance In short term exposure, the rxn is related to the

dose and time i.e. the longer the exposure and the higher the concentration of the harmful agent the more marked the rxn becomes.

Cumulative irritants attributed to prolonged exposure to an agent which is either Present in low concentration and in low toxicity So that the two factors combined are sufficient

enough to ○ Induce and maintain inflammatory skin change

Allergic contact Dermatitis(ACD) Is type IV – delayed hypersensitivity reaction that

affects previously sensitized individual only The two distinct phases in type IV

hypersensitivity are: ○ The induction (sensitization) and ○ The elicitation phase

During the induction phase An allergen (or hapton ) penetrate the epidermis

where it is picked up and processed by an antigen- processing cell (Langerhan cells, dermal dendrocytis and macrophages)

The processed antigen is presented to the T-lymphocytes which undergoes blastogenesis in the regional lymph nodes

One subset of the T-cells differentiate in to memory cells where the other become effecter T-lymphocyte that are released in to the blood stream

The elicitation phase occurs when the sensitized individual again is exposed to the antigen

The processed antigen is presented to the circulating effecter T-lymphocyte that, in turn,

Produce lymphokins These lymphokins mediate the

inflammatory response that is characteristic of A.C.D

Contact Dermatitis can be a. Acute

○ Erythema, edema, vesiculation, weeping and formation of crusts

b. Subacute ○ excoriation and scaling

c. Chronic ○ Lichenifection

Allergic contact Dermatitis ACD accounts for 20% of all CDDDX between patch Test reactions of irritant and

allergic origin

Reaction ICD ACD

Reaction in previously unexposed normal Voluntary + -

Reaction extends beyond test site

- +

Reaction away from site, e.g. flaring up of old eczematous lesions, allergic eruption

- +

Reaction becomes more pronounced days after removal of test strip

- +

Allergens causing Contact Dermatitis by areasSite Cause

1. Scalp All cosmetics including hair dyes and hair conditioners, shampoos. The scalp is highly resistant to allergens whose effects tend to manifest themselves on the adjacent skin (eyelids, ears, neck, face), and on the hands.

2. Eyelids Agents coming into contact with the scalp, face or hands, especially nail polish. Aerosol allergens such as fragrances, insecticides, cleaning agents, furniture polish, vegetable oils, woods, synthetic resins, nasal sprays, cleansing agents for contact lenses.

3. Forehead Hat bands (chromates) and agents with which hats are impregnated (laurel oil, plastics)

4. Face All cosmetics used on or near the face.

5. Glabella and retroauricular region

Eye glass parts, hearing aids.

Ear lobes Ear

5. Ear lobes Earrings, especially in nickel allergy ( Costume, Jewelry)

6. Nasal region Nasal ointments and drops, sprays, fragrances, scented handkerchiefs (menthol).

7. Lips and perioral areas

Toothpastes, mouthwashes, citrus fruit and other foods, preservatives and dyes in foods, lipsticks, tipped cigarettes, cigars, cigar holders.

8. Neck and shoulders

Collars, fragrance, nail polish , cosmetics, dyestuffs in clothes, jewelry.

9. Axillae Deodorants, anhidrotics, depilatories, dress shields (often sewn in invisibly), dyes and other chemicals in clothing, fragrances.

10.Hands, back of the hand, lower arms

Detergents and cleaning agents, chromate dermatitis (cement). Palm: plastics or dyestuffs from steering wheel. Dorsal surfaces of fingers: rubber gloves. Index finger: spectacle frame, writing utensils. Hypersensitivity to ointments and suppositories inserted with the fingers.Hypersensitivity to plants, including bulbs. Any occupations.

Ear lobes Ear lobes

11. Trunk Clothes, bath additives, soaps, contents of pockets metal parts in clothing not in immediate contact with the skin.

12.Genitals Contraceptives, intimate hygiene preparations, fragrance, therapeutic preparations, any agents applied to the genitals by hand.

13.Buttocks Toilet seat, cushion covers, seats

15.Perianal region Suppositories or ointments used for hemorrhoids, substances reaching the area via the gastrointestinal tract, purgatives.

16.Thigh Suspenders, contents of trouser pockets, detergents in underwear, inside clothing

17.Leg Stocking fabric, stocking dyes, ulcer treatment lanolin-derivatives.

18.Feet Especially on the back of the big toe: shoes, chromium-tanned leather, leather dyes, plastics, shoe creams, (adhesives), antifungal, antifugals, anhidrotics, prophylactic agents against tinea pedis (Formaldehyde)

Epidemology

Pediatric Contact Dermatitis Exceedingly common –amounting for 4-

7% of all dermatologic consultation Is among the top 10 for pt visits to 10

care clinics

E.g. each year, 10 -50 million peoples in the united state develop allergic rush after contact with

a. Poison Ivy

b. Poison Sumac

c. Poison Oak

The incidence of contact dermatitis in the pediatric age group is debatable but approximately 20% the children are affected at some time

Approximately 20% - 35% of healthy children react to one or more allergens on standard patch tests

Children of parents who experience C.D. are 60% more likely to have positive patch test

Commonestst allergens USA or Europe are Benzocaine Neomycin Lanolin

Each country has a small number of locally unique topical medications E.g. Rhus dermatitis is extremely but

virtually non existent in Europe ሳማ በኢትዮጵያ

Race, sex and age related demographics CD affects whites> than other races ACD + ICD are twice as common in females

than males Nickel is the most frequent contact allergen in

females older than 8 years

e.g. in one study

reaction to Nickel Sulphate occurred in 16 % of children but occurred in 25% of girls aged 14 – 15 years and in only 4.5% of boys aged 6 – 13 years.

C. Dermatitis is age related Infants are more likely to have ICD

in the diaper area Toddlers and other children become

increasingly exposed to poison oak, poison sumac

Adolescents are more likely to develop Irritant reactions form excessive exposure to

soaps A C D to Nickel and preservative in creams

and lotions The recent trend of piercing ears in infants

and body piercing by adolescents can be expected to lower the average age at which Nickel allergy occurs.

Prognoses Depends on

The cause and the possibility of avoiding repeated or continued exposure to the causal allergies or irritants

Long term success in Rx is poor if the correct diagnosis and offending agent are not identified

Some ubiquitous allergies, such as rubber or Nickel, are impossible to totally avoid

Some allergies probably are still un known

New sensitivities to topical medications or other substances may develop during the course of dermatitis Sensitivity to gloves may complicate

dermatitis of the handsSensitivity to Neomycin may complicate

course when applied to infected dermatitis

CD of the hands is generally of mixed origin, Caused by alternative or simultaneously

exposure to allergens and irritants The barriers function of the skin may not

improved for months or even years after episode of the dermatitis

In appropriate Rx with irritants or allergies such as over zealous use of cleansers and antiseptics may worsen the condition