Dermatitis/Eczema

Question 1

What is the definition of hyperkeratosis?

Answer 1

Increased thickness of keratin layer

Question 2

What does parakeratosis mean?

Answer 2

Persistence of nuclei in the keratin layer

Question 3

What does acanthosis describe?

Answer 3

Increased thickness of the epidermis

Question 4

What does spongiosis mean?

Answer 4

Oedema between keratinocytes

Question 5

What does inflammatory cell infiltrate describe?

Answer 5

Acute or chronic lymphocytes and/or neutrophils

Question 6

Are dermatitis and eczema the same thing?

Answer 6

Yes-skin lesions with similar clinical and pathological features but different pathogenic mechanisms (i.e different causes)

Question 7

What are the clinical features of dermatitis and eczema?

Answer 7

Itchy, ill-defined, erythematous and scaly lesions

Question 8

Describe the acute phase of eczema/dermatitis?

Answer 8

Papulovesicular, erythematous lesions, oedema (spongiosis), ooze/scaling and crusting

Question 9

Describe the chronic phase of eczema/dermatitis?

Answer 9

Thickening (lichenification), elevated plaques, increased scaling

Question 10

What are the different types of dermatitis?

Answer 10

Contact allergic (type 4 reaction, spongiotic dermatitis)
Contact irritant (due to trauma (e.g soap), spongiotic dermatitis)
Atopic (genetic and environmental factors resulting in inflammation, spongiotic dermatitis)
Drug related (type 1/4 reaction, spongiotic dermatitis, eosinophils)
Photo-induced/Photosensitive (reaction to UV, may be secondary to photosensitising drugs, spongiotic dermatitis)
Lichen simplex (scratching, well-defined edges, spongiotic dermatitis, external trauma)
Stasis dermatitis (hydrostatic pressure causing trauma, spongiotic dermatitis, extravasation of RBC)

Question 11

How does contact allergic dermatitis arise?

Answer 11

Langerhans cells process antigen in epidermis and present it to Th cells in dermis, sensitised Th cells migrate into lymphatics and then to regional nodes where antigen presentation is amplified

Question 12

What happens on subsequent antigen challenge in contact allergic dermatitis?

Answer 12

Specifically sensitised T cells proliferate, migrate and infiltrate skin

Question 13

How are triggers of contact allergic dermatitis identified?

Answer 13

By patch testing = batteries of allergens placed in small wells and applied to back skin, left in place for 48 hrs and reactions checked after 96 hrs

Question 14

What kind of irritation occurs in contact irritant dermatitis?

Answer 14

Non-specific physical irritation rather than a specific allergic reaction

Question 15

What may contact irritant dermatitis be confused with?

Answer 15

Contact allergic dermatitis (may also overlap with atopic eczema)

Question 16

What may contact irritant dermatitis impact?

Answer 16

The patient’s occupation

Question 17

How common is atopic eczema?

Answer 17

Affects up to 25% of school age children

Question 18

How can atopic eczema have a wider impact on the patient’s life?

Answer 18

Itch leads to sleep disturbance which causes neurocognitive impairment, affects whole family

Question 19

What is another name for atopic eczema?

Answer 19

Atopic dermatitis

Question 20

What are some features of atopic eczema?

Answer 20

Pruritus, ill-defined erythema and scaling, generalised dry skin, flexural distribution (varies with age), associated with other atopic disease

Question 21

Does atopic eczema manifest the same way in skin of colour?

Answer 21

No

Question 22

What are some chronic features of atopic eczema?

Answer 22

Lichenification, excoriation, secondary infection

Question 23

What does crusting of atopic eczema indicate?

Answer 23

Staph. aureus infection

Question 24

What’s a complication of atopic eczema?

Answer 24

Eczema herpeticum = herpes simplex virus, monomorphic punched-out lesions

Question 25

What is the UK diagnostic criteria for atopic eczema?

Answer 25

Itching plus 3 or more of:
Visible flexural rash (cheeks/extensor surfaces in infants)
History of flexural rash
Personal history of atopy (or 1st degree relative if < 4 years old)
Generally dry skin
Onset before age 2

Question 26

What are some treatments of atopic eczema?

Answer 26

Plenty of emollients, avoid irritants, topical steroids, phototherapy (mainly UVB), systemic immunosuppression, biologic agents

Question 27

What are important in the development of atopic eczema?

Answer 27

Skin barrier function, environmental factor, immunology, the filaggrin gene

Question 28

What are some other variants of dermatitis/eczema?

Answer 28

Discoid eczema (patients often atopic), Seborrhoeic dermatitis, Pompholyx eczema (spongiotic eczema)