Allergic Contact and Irritant Contact Dermatitis

Question 1

how common is allergic contact dermatitis

Answer 1

very common

Question 2

give 2 examples of allergic contact dermatitis

Answer 2

nickel belt buckle, rubber glove

Question 3

what cell processes the antigen in the epidermis

Answer 3

Langerhans cells

Question 4

describe the role of Th cells in the immunopathology of allergic contact dermatitis

Answer 4

processed antigen presented to Th cell in dermis, sensitised Th cells then migrate to lymphatics and then regional nodes where antigen presentation amplified

Question 5

what is the role of T cells in the immunopathology of allergic contact dermatitis

Answer 5

on antigen challenge specifically sensitised T cells proliferate and migrate to and infiltrate the skin
resulting in dermatitis

Question 6

how can specific substances causing allergic contact dermatitis be identified

Answer 6

patch testing

Question 7

what is the difference between irritant (contact) dermatitis and allergic contact dermatitis

Answer 7

irritant in non-specific physical irritation rather than specific allergic reaction
(can be difficult to distinguish)

Question 8

what are some clinical features associated with irritant contact dermatitis

Answer 8

erythema, scaling, fissuring, lichenification, nail dystrophy, crusting

Question 9

what is spared in irritant contact dermatitis

Answer 9

flexures

Question 10

give some examples of irritant contact dermatitis

Answer 10

“lip lick” chelitis, “nappy rash” to urine, mechanical oils, nickel belt buckle/ring