Contact dermatitis

Question 1

What is contact dermatitis?

Answer 1

An inflammatory skin condition affecting the epidermis and the dermis, which occurs as a result of exposure to an external irritant or allergen.

Question 2

What is allergic contact dermatitis defined as?

Answer 2

a type 4 hypersensitivity reaction that occurs after sensitisation and subsequent re-exposure to a specific allergen.

Question 3

What is irritant contact dermatitis defined as?

Answer 3

a non-immunological inflammatory reaction caused by the direct physical or toxic effects of an irritating substance on the skin - prior sensitisation is not required

Question 4

What is acute irritant contact dermatitis?

Answer 4

Acute irritant contact dermatitis typically occurs following a single overwhelming exposure or a few brief exposures to strong irritants.

Question 5

what is chronic irritant contact dermatitis defined as?

Answer 5

occurs following repeated exposure to weaker irritants such as detergents, soaps, dust or low humidity air.

Question 6

Can allergic and irritant contact dermatitis co-exist?

Answer 6

yes

Question 7

What are 5 common allergens?

Answer 7

1. Personal care products such as cosmetics, skincare products, nail varnish, fragrances, sunscreen, and hair dye.
2. Metals such as nickel and cobalt (often found in jewellery) and chromate (in cement) – nickel is the most common allergen.
3. Topical medications including anti-infective agents and topical corticosteroids.
4. Rubber additives (often found in footwear).
5. Plants – those in the Compositae group (chrysanthemum and sunflowers), daffodils, tulips, and primula are the most common.

Question 8

What are common irritants?

Answer 8

Water, in particular repeated or prolonged contact, such as with wet working conditions.
Sweating under occlusion.
Detergents, soaps, and cleaning agents.
Solvents and abrasives.
Machine and cutting oils.
Acids and alkalis (including cement).
Reducing agents and oxidizing agents (including sodium hypochlorite).
Powders, dust, and soil (such as exotic woods and cement).
Certain plants such as ranunculus, spurge, Boraginaceae and mustards.

Question 9

What is the most common irritant in the first year of life?

Answer 9

NAPPY CONTACT

Question 10

What is the world prevalence of contact dermatitis?

Answer 10

20%
with 80% of these cases being irritant contact dermatitis and 20% being allergic contact dermatitis

Question 11

What are 6 clinical features of contact dermatitis?

Answer 11

1. Itching
2. burning
3. stinging
4. erythema
5. scaling
   6.fissuring

Question 12

What should be included in a history for contact dermatitis?

Answer 12

1. Possible precipitating, aggravating and relieving factors
   -Substances causing allergic contact dermatitis may have been in use for some time.
   -If a potential allergen or irritant is identified, ask about the amount and duration of contact, and time between exposure and development of symptoms.
2. Occupations past and present
   - Certain occupations (including those with frequent exposure to water and the use of detergents) may increase the risk of dermatitis.
   -Check if symptoms improve at weekends and during holidays, and recur on return to work.

3.Household and recreational activities such as cleaning, hobbies (for example, gardening, home improvement, and painting), and some sports.

4.Past medical history including previous history of similar rashes or atopy.

5. Family history of skin conditions or atopy.

Question 13

What can cause contact dermatitis on the face?

Answer 13

Contact dermatitis of the face due to fragrances, hair dyes, skincare products, cosmetics, and nail varnish is common.

Question 14

What can cause contact dermatitis on the eyelids?

Answer 14

he eyelids may be directly affected by cosmetics or contaminated by the fingers (for example with nail varnish), airborne droplets (for example fragrance sprays), or volatile substances (for example epoxy resin).

Question 15

What can cause contact dermatitis on the ears?

Answer 15

many irritants and allergens including topical medications, earrings, or spectacle frames can cause contact dermatitis of the external ear.

Question 16

What can cause contact dermatitis on the Scalp?

Answer 16

hair dyes are a common cause of contact dermatitis of the scalp.

Question 17

What can cause contact dermatitis on the neck?

Answer 17

nickel in jewellery or zips or airborne allergens (such as from plants) can cause contact dermatitis on the neck.

Question 18

What can cause contact dermatitis on the axillae?

Answer 18

contact dermatitis can be caused by irritation from sweating, occlusion, or use of antiperspirants.

Question 19

What can cause contact dermatitis on the ano-genital area?

Answer 19

topical medications (prescribed and over-the-counter) such as those used in the treatment of pruritus or haemorrhoids may contain allergens including fragrance, local anaesthetics, or balsam of Peru.

Question 20

What can cause contact dermatitis on the lower legs?

Answer 20

allergic contact dermatitis from topical treatments (such as antibiotics and creams) and dressings can occur in people with varicose eczema and ulcers.

Question 21

What can cause contact dermatitis on the feet?

Answer 21

leather, rubber, glues, and nickel in footwear, stockings, topical medications, antiseptics, and antiperspirants can cause contact allergy of the feet.

Question 22

What is the gold standard test for contact dermatitis?

Answer 22

Patch testing

Question 23

Give 5 conditions included under the contact dermatitis umbrella:

Answer 23

1) chemical burns
2) irritant contact dermatitis
3) allergic contact dermatitis
4) contact stomatitis
5) contact chelitis

Question 24

What is chelitis?

Answer 24

inflammation of the lips

Question 25

What is stomatitis?

Answer 25

inflammation of the oral mucosa

Question 26

Give 4 occupations at particular risk of contact dermatitis:

Answer 26

1) cleaners
2) healthcare workers
3) food handlers
4) hair dressers

Question 27

Give 7 skin features of contact dermatitis:

Answer 27

1) erythema
2) blistering or bullae
3) oedema
4) dryness or scaling
5) cracks
6) lichenification
7) hyper/ hypopigmentation

Question 28

Differential diagnosis for contact dermatitis?

Answer 28

1. Fungal infection eg tinea corporis
2. Bacterial infections eg cellulitis and impetigo
3. Viral infection eg herpes simplex or variella zoster
4. Urticaria
5. Psoriasis
   6.Lupus erythematosus
6. Dermatomyositis.
7. Mycosis fungoides.
8. Fixed drug eruption.
9. Photosensitivity.
10. Lichen planus of the hands.
11. Basal cell carcinoma.

Question 29

How should a patient with contact dermatitis be manage in primary care is causative agent is identified?

Answer 29

Advise the person that avoidance of the stimulus is the most important element of treatment and prevention of recurrent episodes of contact dermatitis.

8–12 weeks of avoidance may be needed before clinical improvement is seen — in some cases, contact dermatitis may persist and require long-term treatment.

Advise the use of liberal emollient and soap substitutes to maintain skin hydration and improve barrier repair.

Advise the person that they must not smoke, use naked flames (or be near people who are smoking or using naked flames), or go near anything that may cause a fire while emollients are in contact with dressings, clothing, or bedding.

Do not prescribe aqueous cream as it is thought to cause a disproportionate amount of skin reactions.

Consider the need for topical corticosteroids.
Topical steroids may be required to control symptoms

Question 30

What should be advised to a patient with contact dermatitis where avoidance of the stimulus is not possible?

Answer 30

insing with water or washing with soap or, preferably, a soap substitute as soon as possible after contact (overuse of skin-cleaning agents can aggravate contact dermatitis).

Substituting products that contain identified allergens or irritants with other products that do not contain them.

Use of gloves (cotton-lined rubber or plastic) for handling potential irritants — certain chemicals may require heavier-duty protective materials. Gloves should be removed frequently, as sweating may aggravate existing dermatitis.

Avoidance of accumulation of chemicals and water underneath jewellery.

Question 31

When should referral to dermatology be considered?

Answer 31

-Dermatitis
-Previously stable dermatitis has become difficult or impossible to control with standard treatments.
Allergy to prescribed or over-the-counter topical treatments is suspected.
-Suspected contact dermatitis does not respond to treatment in primary care, has atypical features (other diagnoses should be considered), or the diagnosis is unclear.
-Contact dermatitis is thought to be associated with occupation.

Question 32

Give 6 common causes of contact dermatitis:

Answer 32

1) soaps
2) detergents
3) acids/alkali
4) solvents
5) foods
6) frictional injury

Question 33

Give 3 treatments used to manage severe or chronic cases of contact dermatitis:

Answer 33

1) oral corticosteroid (e.g. prednisalone)
2) immunosuppressant
3) phototherapy

Question 34

Name 3 immunosuppressants that can be used to treat severe/chronic contact dermatitis:

Answer 34

1) methotrexate
2) ciclosporin
3) azathioprine