Contact Dermatitis

Question 1

What are the types of contact dermatitis?

Answer 1

Irritant contact dermatitis
Allergic contact dermatitis

Question 2

How does allergic contact dermatitis work?

Answer 2

Type IV hypersensitivity reaction to external antigen

Direct contact/airborne/injection -> Langerhans cells generate T cells -> sensitised Th cells respond to antigen, releasing inflammatory cytokines and cell mediated cytotoxicity

Question 3

How does allergic contact dermatitis work?

Answer 3

Type IV hypersensitivity reaction to external antigen

Direct contact/airborne/injection -> Langerhans cells generate T cells -> sensitised Th cells respond to antigen, releasing inflammatory cytokines and cell mediated cytotoxicity

Exposure leads to characteristic skin findings after a couple days

Question 4

How is allergic contact dermatitis investigated?

Answer 4

Patch testing-
Allergens put on Finn chambers which are applied to back for 48hrs

Readings taken at 48 and 96 hours to account for Hypersensitivity IV delay

Question 5

What is irritant contact dermatitis

Answer 5

Non specific physical irritation caused by an irritant, eg soap, water, oils, cleaning products

NOT caused by allergens, non immunological process

Question 6

How is contact dermatitis managed?

Answer 6

Identify and avoid causative irritant/allergen

Topical steroids emolients for inflammation management and restoring skin hydration