Dermatitis

Question 1

aetiology of contact allergic dermatitis

Answer 1

in response to chemicals, perfume, nickel, latex, plants

Question 2

presentation of contact allergic dermatitis (location, worse areas)

Answer 2

location - around the site of irritation

worse at thin skin

Question 3

what is the immunological response in contact allergic dermatitis (5 steps and hypersensitivity type)

Answer 3

type IV hypersensitivity - delayed response

1. Langerhans process antigen
2. antigen passed on to T helper cells in dermis
3. T helper cells take antigen to lymphatics
4. antigen presented to other cells
5. when antigen is encountered again = recognised = T cells proliferate and migrate to skin = dermatitis

Question 4

what investigation would you do if you suspected contact allergic dermatitis

Answer 4

patch test

blood IgE

Question 5

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

Answer 5

contact irritant dermatitis doesnt involve IgE (NOT an allergic response)

Question 6

aetiology of contact irritant dermatitis

Answer 6

soap, detergents, cleaning products (eg under jewellery)

urine = nappy rash
lick lip dermatitis

Question 7

aetiology of atopic eczema/atopic dermatitis

Answer 7

genetic (filaggrin mutation = filament aggregating protein)

environmental factors

Question 8

what other conditions are associated with atopic eczema

Answer 8

asthma, rhinitis, food allergy

Question 9

what age does eczema typical present

Answer 9

school aged children

Question 10

what does atopic eczema look like on histology

Answer 10

spongiosis (white spaces in cells = looks like a sponge) and inflammatory infiltrate

NOTE - all other dermatitis have spongiosis on histology, but no inflammatory infiltrate

Question 11

first line treatment of atopic eczema

Answer 11

emollients (eg e45) to soothe and hydrate

avoid irritants

Question 12

second line treatment of atopic eczema (after emollients)

Answer 12

topical steroids

Question 13

third line treatment of atopic eczema (after emollients and topical steroids)

Answer 13

treat infection
phototherapy
immunosuppressants

Question 14

how does chronic eczema present

Answer 14

excoriations (scratch marks)
lichenification - thickening of skin bc of scratching
may be infected

Question 15

how does staph aureus infected chronic eczema present

Answer 15

yellow crusting

Question 16

aetiology discoid eczema

Answer 16

scratching of dry skin and irritation of skin

Question 17

how does discoid eczema present

Answer 17

red plaques in well defined discs (DISCoid eczema)

can appear anywhere, unusual on face/scalp

Question 18

what is pompholyx eczema associated with

Answer 18

oedema

Question 19

how does photoinduced dermatitis present

Answer 19

stops at collar level

Question 20

aetiology of lichen simplex dermatitis

Answer 20

scratch = itch cycle

Question 21

location of lichen simplex dermatitis

Answer 21

back of neck, side of legs

Question 22

aetiology of stasis dermatitis

Answer 22

hydrostatic pressure (eg oedema) = skin under pressure

Question 23

what can stasis dermatitis predispose

Answer 23

venous leg ulcer

Question 24

how do all dermatitis present on histology

Answer 24

spongiosis (white spaces in between cells = look slike a sponge)

Question 25

what 2 infections are associated with dermatitis

Answer 25

herpes simplex virus infection | staph aureus infection

Question 26

how does herpes simplex virus associated with dermatitis present

Answer 26

monomorphic punched out lesions

Question 27

what does herpes simplex virus infection associated with dermatitis cause

Answer 27

eczema herpeticum

Question 28

how does staph aureus infection associated with dermatitis present

Answer 28

yellow crusting

Question 29

how does staph aureus manage to infect someone with dermatitis

Answer 29

scratching of skin = skin becomes broken

Question 30

how is staph aureus infected dermatitis treated

Answer 30

PO flucloxacillin

Question 31

hypersensitivity of contact allergic dermatitis

Answer 31

type IV hypersensitivity - delayed response

Question 32

which cells process the antigen in contact allergic dermatitis

Answer 32

Langerhans

Question 33

what is the role of T cells in contact allergic dermatitis

Answer 33

Langerhans pass on antigen to T helper cell | T helper cell takes antigen to lymphatics

Question 34

why does the lymphatics take the antigen in contact allergic dermatitis

Answer 34

to present it to other cells whenever any of them come in contact with it again = dermatitis occurs

Question 35

which condition is filagrin associated with

Answer 35

atopic dermatitis/eczema

Question 36

what is filagrin

Answer 36

filament aggregating protein

Question 37

why doesnt everyone with filagrin get eczema

Answer 37

need skin barrier to be impaired