Contact Dermatitis

Question 1

Define contact dermatitis

Answer 1

An inflammatory skin condition caused by allergens or irritants
Causes erythematous, pruritic and potentially vesicular rashes at site of contact.

Question 2

What type of reaction is allergic contact dermatitis?

Answer 2

Type 4 delahed hypersensitivity
Meaning symptoms typically present 2-3 days after re-exposure to allergen, pruritus tends to be the major concerns

Question 3

What is the process underpinning irritant contact dermatitis?

Answer 3

More common than allergic
substance sources direct damage to skin -> remove oils, causing dryness, itch and inflammation
Can occur on top of allergic

Question 4

What are the common triggers for irritant contact dermatitis?

Answer 4

Detergents, soaps, cleaning products
Acids and alkalis
Often seen in frequent hand washing or industrial jobs
Worsened by low humidity

Question 5

What are the common triggers for allergic contact dermatitis?

Answer 5

Nickel
Fragrances
Rubber accelerators
Preservatives in personal care products

Pften history of atopy or HLA markers

Question 6

What are some unique classifications of contact dermatitis?

Answer 6

Phototoxic and photoallergic - requires irritant/allergen and sunlight
Systemic -> sensitised individual ingests or inhels and gets widespread dermatitis
Pigmented -> rather than typical rash skin becomes more pigmentated with contact

Question 7

What are the symptoms of contact dermatitis in the acute phase?

Answer 7

Erythema -> capillary dilation
Vesicles and bullae (severe)
Oedema -> serous fluid accumulation
Pruritus -> most common

Question 8

What are the symptoms of contact dermatitis in the chronic phase?

Answer 8

Lichenification
Fissuring - due to dryness and reduced elasticity
Hypo/erpigemtnations -> melanocyte stimulation changes

Question 9

What is the gold standard investigations for an allergic contact dermatitis?

Answer 9

Patch testing -> allergen to skin for 48hrs

Question 10

What investigations may be done for a suspected contact dermatitis?

Answer 10

Patch testing
Skin biospy
Lab tests -> HIV, Hep C, IgE (pos in atopic not allergy)

Question 11

What is the recommended management for contact dermatitis?

Answer 11

Avoidance of offending agent
Topical corticosteroids for acute flares
Emollients for symptomatic relief
May refer to derm is symptoms persist despite appropriate management.

Question 12

What are some complications of contact dermatitis?

Answer 12

Secondary infections -> impetigo or cellulitis
Chronic skin changes -> lichenification, pigment changes
Mental health -> anxiety and depression
Sensitivity spread -> widespread allergic reactions