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Flashcards in Allergies at Home and Work Deck (26)
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What is the difference between Atopic Dermatitis and Contact Dermatitis?

Contact dermatitis - external cause

Atopic dermatitis - internal cause.


What is the difference between Allergic Contact Dermatitis and Irritant Contact Dermatitis?

  • Allergic Contact Dermatitis - contact to the skin has previously caused a type 4 immune mediated hypersensitivity reaction.
  • Irritant Contact Dermatitis - due to direct irritant on the skin.


What are the substances that most commonly cause irritant contact dermatitis? ICD

  1. Water
  2. Detergents
  3. Soaps
  4. Solvents
  5. Abrasives
  6. Alkalis
  7. Acids
  8. Cement
  9. Cutting oils
  10. Plants
  11. Dust
  12. Soil


What % of men and women have hand eczema?

5% of men and 10% of women have hand eczema.


What is the most common area of the body to get irritant contact dermatitis?



Is this Irritant Contact Dermatitis or Allergic Contact Dermatitis?

This is Irritant Contact Dermatitis due to the soap collecting underneath the ring.

Allergic Contact Dermatitis would be due to a nickel allergy and would look different.


What is this and what causes it?

Eczema Craqulee

It is usually due to chronic episodes of ICD - where the skin hasn't healed properly.


How does one manage irritant dermatitis?

Prevention is key

  • Use gloves.
  • Treat flares with topical steroids.
  • Treat secondary infections
  • KNMO4 soaks for pompholyx eczema.


What is the pathophysiology of Allergic Contact Dermatitis (ACD)?

It is a Type 4 Hypersensitivity Reaction.

Langerhans cells in the epidermis present the antigen to the T Lymphocytes and then sensitisation occurs.


What is the management for Allergic Contact Dermatitis?

  1. Detect the likely sensitising agent.
  2. Patch testing - once dermatitis has settled down.


What is used in a patch test?

The European Standard Battery Test (ESB)

is composed of 35-38 different substances

which are the most common to cause ACD.


Where are the patch tests placed?

On the back


How long is the skin patch left on for?

48 hours


When are the skin patches read by the Doctor?

At 72-96 hours.


What are some other sorts of patch tests? (specialist tests)

Some specialists kits include:

The Florist series.

The Dental series.

The hairdresser series



Who should be patch tested?

Patients who have the following patterns of eczema:

  • Eyelid, face, perioral
  • Otitis externa
  • Gand/foot dermatitis
  • Perianal or genital eczema
  • Unusual/ asymmetrical patterns of eczema
  • Sudden deterioration of long-standing eczema
  • Certain occupations (see above)


What are the most common contact allergens?

  1. Nickel
  2. Chromate (in cement, plaster, leather matches, polish)


What are the 3 most common culprits for foot ACD?

  1. Chromate
  2. p-tert-Butylphenol-formaldehyde resin - shoe adhesive.
  3. Thiuram - leather accelerators. 


What are the types of hand dermatitis and their causes?

  1. Irritant Contact Dermatitis - powder/soap/gloves/sweaty hands.
  2. ACD - thiuram accelerator in leather gloves.
  3. Type 1 Allergy to latex
    • ​​Detected by prick testing or RAST IgE test.


If someone has a latex allergy, what should they be told to avoid?

Rubber balloons

Swimming hats

Rubber Contraceptives (cap and condom)

Latex gloves.


What is the chemical in hair dyes and henna that can cause an allergic reaction?

Paraphenylenediamine (PPD)


What are some causes of anogenital dermatitis?

  • Haemorrhoid creams (which contain LA)
  • Antiseptics (Chlorhexidine)
  • Antibiotics (neomycin)


If someone has anogenital dermatitis and demands to see a dermatologist,

what should you do?


- have a low threshold for referral.


What can be used in the patch test to see if someone has an allergy to steroids?

Tixocortol Pivalate.


If someone shows an allergy to tixocortol pivalate, what should they avoid and what can they still use?

Avoid: Dermovate and Hydrocortisone.

Safe to use: Betnovate and Mometasone.