Contact dermatitis

28 May

Contact dermatitis is the inflammation (-itis) of the skin (derma) in response to contact with particular substances (allergens or irritants). The impacted area of the body depends on the site of contact. Inflammation usually clears up once the substance has been removed/avoided.

- Estimated by the International Workshop on Contact Dermatitis and the JAMA network found that 1 in 5 or 20% of the general population suffer from allergic contact dermatitis. [1,2]
- NICE guidelines found that contact dermatitis accounts for 4–7% of dermatological consultations in secondary care.
- Irritant contact dermatitis is more common than allergic contact dermatitis — up to 80% of contact dermatitis is irritant.
- About two-thirds of all cases of contact dermatitis involve the hands.
- Contact dermatitis tends to be most common in young females, this is due to an increased level of exposure to substances in jewellery (such as nickel) and cosmetics.
- Between 13-34% of all occupational diseases are skin diseases; of these diseases, 90-95% are contact dermatitis. [3]
- Allergens
  - Cosmetics
  - Metals such as nickel or cobalt
  - Topical medicines such as topical corticosteroids
  - Rubber eg. latex
  - Textiles eg. dyes and resins
  - Strong glues
  - Some plants such as sunflowers, tulips, daffodils etc.
- Irritants
  - Soaps and detergents
  - Disinfectants
  - Cement
  - Perfumes and toiletries
  - Powders, dust and soil [5]
Medical Students
Types:
- Allergic Contact Dermatitis (ACD): Triggered by allergens
- Irritant Contact Dermatitis (ICD): Triggered by irritants
Allergic Contact Dermatitis:
- Type IV hypersensitivity reaction (T cell-mediated, delayed)
- Nickel sulphate is the most common allergen globally
- Two main phases:
  1. Sensitisation Phase:
    Langerhans cells capture allergens and trigger the innate immune system
    Antigens transported to lymph nodes
    Presented to naive antigen-specific T cells
    T cells undergo expansion and differentiation into memory/effector T cells
    T cells acquire cutaneous homing receptors
  2. Elicitation Phase (on re-exposure):
    T cells migrate to skin
    Recognise antigen and release inflammatory cytokines
    Inflammatory response at site of contact
- Sensitisation can take days to years depending on allergen strength
Irritant Contact Dermatitis:
- Non-specific inflammatory reaction (no immune memory)
- Triggered by acids, solvents, soaps, plants, chronic moisture (urine/saliva)
- Acute ICD: Immediate skin damage from strong irritants, burning/stinging
- Chronic ICD: Requires repeated exposure to milder irritants, presents with pruritus (itch)
Patients
Allergic Contact Dermatitis:
- Caused by the body’s immune system reacting to an allergen
- Most common allergen: Nickel sulphate
- Two stages:
  1. Sensitisation:
    Body first exposed to the allergen
    Cells capture allergen and carry it to lymph nodes
    Immune cells (T cells) learn to recognise the allergen and multiply
  2. Allergic Reaction (after re-exposure):
    T cells move to the skin and cause inflammation at contact site
- This immune memory means reactions can occur long after first exposure
Irritant Contact Dermatitis:
- Caused by direct skin damage from irritating substances
- Common irritants: chemicals, soaps, plants, moisture (urine, saliva)
- Short-term exposure (strong irritants) can cause pain, burning, redness
- Long-term exposure (weaker irritants) causes itchy, inflamed skin over time [4]
- Females are more likely to suffer from irritant dermatitis due to exposure to jewellery and fragrances
- History of atopic dermatitis
- Occupation with high levels of exposure to irritants [6]
- Painful in irritant contact dermatitis
- Erythema (redness)
- Scaling skin
- Swelling (oedema)
- Crusting
- Blistering
- Itchiness [4]
- Occupational history of exposure
- History of atopic dermatitis
- Previous episodes of similar dermatitis
- Referral to a dermatologist
- Patch test
  - Potentially triggering substances are attached to an area of the body using tape
  - Can be attached to places like the upper arm, the back or the forearm.
  - 2 days later, the patches are removed and assessed to note any reactions.
  - Can be accessed 2 days post initial investigation as atopic dermatitis reactions can appear later [5]
- Erythema multiforme (an allergic reaction to medicine/infection)
- Uriticarial (relating to itchiness) papular plaques (pattern of plaque formation)
- Lichen planus (itchy rash)
- Pemphigoid (blistering, and itchiness)
- Granulomatous (cell pattern that appears after cell injury)
- Purpuric petechial reactions (purple, small non raised patches) [6]
Students
- Avoid contact with the irritant or allergen
- Topical treatment includes cool compresses (saline or Burow solution) and corticosteroids.
- Patients with mild to moderate acute contact dermatitis are given mid- to high-potency topical corticosteroid
  - Triamcinolone
  - Betamethasone valerate cream
- Oral corticosteroids can be used for severe blistering or long-term presentation
  - Prednisolone
- Systemic antihistamines
  - Hydroxyzine
  - Diphenhydramine help relieve pruritus
- Wet-to-dry dressings can elevate oozing blisters.
- Can also dry skin and aid the healing process.
Patients
- Avoid contact with the irritant or allergen
- Cool compress, which can be applied to the skin and steroids (to reduce inflammation).
- Patients with mild to moderate short-term contact dermatitis are given mid-high effective steroids that can be applied to the skin
  - Triamcinolone
  - Betamethasone valerate cream
- Oral steroids can be used for severe blistering or long-term presentations
  - Prednisolone
- Antihistamines that treat itchiness, and other allergic symptoms
  - Hydroxyzine
  - Diphenhydramine to help relieve itchiness
- Wet-to-dry dressings (dressing used to remove dead skin from a wound by wetting the dressing, placing on affected skin and drying. Then removing the dressing which removes the dead skin).
- This can alleviate oozing blisters. Can also dry skin and aid the healing process. [4]
- Post- inflammatory hyperpigmentation
- Bacterial infection from broken skin due to dermatitis (staphylococcus or streptococcus bacteria)
- Impetigo [7,8]
- Direct contact is necessary for contact dermatitis
- Soft, 100% cotton is the ideal fabric to wear for contact dermatitis
- Gloves protect you against all allergens [9]
- How can I find out what is causing my condition?
- How can I protect myself against allergens/ irritants?
- What can I do to prevent complications of contact dermatitis?
- Is contact dermatitis infectious?
- British Association of Dermatologists
- British Skin Foundation
- Changing Faces Charity
[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3276771/
[2] https://jamanetwork.com/journals/jamadermatology/fullarticle/2775575#:~:text=Allergic
[3] https://cks.nice.org.uk/topics/dermatitis-contact/background-information/prevalence/
[4] https://www.msdmanuals.com/en-gb/professional/dermatologic-disorders/dermatitis/contact-dermatitis?query=contact
[5] https://www.nhs.uk/conditions/contact-dermatitis/causes/
[6] https://www.ncbi.nlm.nih.gov/books/NBK459230/#:~:text=Risk
[7] https://ada.com/conditions/contact-dermatitis/
[8] https://www.verywellhealth.com/contact-dermatitis-symptoms-4685650
[9] https://escholarship.org/uc/item/9rf739t3