Dermatitis/Atopic Eczema

Question 1

What is the preferred term:

Dermatitis or eczema?

Answer 1

Eczema - skin lesions with similar clinical and pathological features but different pathogenic mechanisms (i.e: this is an umbrella term)

Question 2

Acute phase of eczema?

Answer 2

Papulovesicular rash

Erythematous lesions

Spongiosis (oedema)

Ooze or scale and crusting

Question 3

Difference between scaling and crusting?

Answer 3

Scale - dead keratinocytes

Crust - dried tissue fluid or blood

Question 4

Chronic phase of eczema?

Answer 4

Lichenification (thickening)

Elevated plaques

Increased scaling

Question 5

4 main features of eczema?

Answer 5

Pruritic (if it is not itchy, it is not eczema)

ILL-DEFINED (unlike psoriasis)

Erythematous

Scaly

Question 6

Describe atopic eczema

Answer 6

Genetic and environmental factors cause inflammation of the skin that is most common in childhood

Exhibits type I and IV hypersensitivity and, on histology, shows spongitoic dermatitis

Question 7

Describe contact allergic dermatitis

Answer 7

Contact of allergen with the skin causes a delayed (type 4) hypersensitivity reaction; this leads to spongiotic dermatitis on histology

Question 8

Describe contact irritant dermatitis

Answer 8

Non-specific reaction to trauma, e.g: soap, water, leads to spongiotic dermatitis, on histology

NON-ALLERGIC

Question 9

Describe drug-related dermatitis

Answer 9

Can be a type I or IV hypersensitivity reaction

Histologically, there is spongiotic dermatitis and EOSINOPHILS (unique to drug-related dermatitis)

Question 10

Describe photo-induced or photosensitive dermatitis

Answer 10

Reaction to UV light causes spongiotic dermatitis

Rash present on light-exposed regions and sparing under clothes

Question 11

Describe lichen simplex

Answer 11

Physical trauma to skin, such as scratching, leads to thickening of skin, which leads to more itchiness

Histologically, there is spongiotic dermatitis and external trauma

Question 12

Describe stasis dermatitis

Answer 12

Physical trauma to the skin under hydrostatic pressure, e.g: legs, lower back

Histologically, there is spongiotic dermatitis and extravasation of rbcs (leading to brown pigmentation of skin)

Question 13

Give examples of allergens in contact allergic dermatitis?

Answer 13

Very common:

Nickel

Chemicals, e.g: in gloves

Topical therapies

Plants

Question 14

Immunopathology of contact allergic dermatitis?

Answer 14

1. Langerhan cells in the epidermis process the antigen (increased immunogenicity)
2. Processed antigen is then presented to Th cells in the dermis
3. Sensitised Th cells migrate into lymphatics and then to regional nodes where antigen presentation is amplified
4. On re-exposure, sensitised T cells proliferate and migrate to and infiltrate skin, leading to dermatitis

Question 15

What pathological features can be seen in this picture? IMAGE 1

Answer 15

Spongiosis (white spaces between keratinocytes)

Inflammatory infiltrate

Question 16

Diagnosing contact allergic dermatitis?

Answer 16

PATCH TESTING:

Batteries of allergens placed in small wells and applied to back skin

Left in place for 48-96 hrs, checking at both times

Question 17

Differentiating between irritant dermatitis and contact allergic dermatitis?

Answer 17

Difficult; the two may overlap or co-exist

Question 18

5 clinical features seen?

Answer 18

1. Erythematous
2. Erosions (breaks in epidermis)
3. Scaling
4. Lichenification (increased skin markings) and hyperlinearity
5. Nail dystrophy

Question 19

Examples of irritant contact dermatitis?

Answer 19

Nappy rash (irritant contact dermatitis to urine) - flexures are spared

Lip-lick dermatitis (to saliva)

Question 20

How does atopic eczema impact on quality of life?

Answer 20

Very common in children; pruritus leads to sleep disturbance and neurocognitive impairment

This affects the whole family

Question 21

Describe the itch-scratch cycle

Answer 21

Itchiness leads to desire to scratch; but this causes more itchiness

Question 22

Features of atopic eczema?

Answer 22

1. ILL-DEFINED
2. Generalised dry skin
3. Flexural distribution but this varies with age; in infants, it often affects the cheeks and abdomen (also, neck flexure and below earlobes) but, as they grow older, begins to affect the flexures
4. Assoc. with other atopic disease, e.g: asthma, allergic rhinitis, food allergies

Question 23

3 chronic changes with atopic eczema?

Answer 23

1. Lichenification
2. Excoriation
3. Secondary infection (gold crusting indicated Staph. aureus infection)

Question 24

What is eczema herpeticum?

Answer 24

Caused by HSV and SHOULD NOT BE MISSED

Characterised by:

Monomorphic (look the same), punched-out lesions

Systemically unwell child (high fever)

Question 25

Diagnostic criteria for atopic eczema?

Answer 25

Itching + 3/more of: Visible flexural rash\* History of flexural rash\* Personal history of atopy (or in a 1st degree relative if under 4 yrs) Generally dry skin Onset before age 2 years \*cheeks and extensor surfaces in infants

Question 26

Treatment of eczema, from mild to severe?

Answer 26

1. Plenty of emollients 2. Avoid irritants including shower gels and soaps 3. Topical steroids 4. Treat infection 5. Phototherapy – mainly UVB 6. Systemic immunosuppressants 7. (Biologic agents) - mono/poly clonal antibodies against cytokines in the inflammatory pathway

Question 27

What is the most important gene in the development of atopic eczema?

Answer 27

Fillagrin

Question 28

What is discoid eczema?

Answer 28

Scattered, roundish patches of eczema with an unknown cause but is sometimes assoc. with Staph. aureus infection; the rash is WELL-DEFINED making it an exception in eczema Patients are often atopic

Question 29

What is chronic actinic dermatitis?

Answer 29

Rare skin condition mainly affecting men \>50 years. Patients are often atopic Characterised by severely itchy, red, inflamed, and thickened dry skin, mainly in areas that have been exposed to sunlight or artificial light (cut-off at the collar)

Question 30

What is seborrheic dermatitis?

Answer 30

Chronic or relapsing form of eczema/dermatitis that mainly affects the scalp and face

Question 31

What is pompholyx dermatitis?

Answer 31

Hand/foot eczema characterised by spongiotic vesicles or bullae (vesicular dermatitis)

Question 32

What is lichen simplex?

Answer 32

Localised area of chronic, lichenified eczema/dermatitis Follows repetitive scratching/rubbing due to chronic, localised itch, often on back of head and top of foot ; it is more common in people with anxiety or OCD

Question 33

What histological features are shown in the biopsy: a: Spongiosis b: Inflammatory infiltrate c: Dermal hyperplasia d: Epidermal hyperplasia e: a and b

Answer 33

e

Question 34

How would you distinguish between irritant and allergic contact dermatitis in this patient: a: Occupational history b: Family history c: Social history d: Patch testing e: All of the above

Answer 34

e

Question 35

What does this patch test result show? a: Contact allergic reaction to multiple specific allergens b: Contact allergic reaction to tape adhesive c: a and b d: The patient does not have contact allergy e: Rare ‘blue’ reaction

Answer 35

c

Question 36

What type of dermatitis does this 6 month old baby have: a: Allergic contact b: Irritant contact c: Atopic eczema d: Psoriasis e: Candida (thrush)

Answer 36

b

Question 37

What has caused this rash and what would you do: a: Atopic eczema, treat with steroids b: Contact allergic reaction to nickel, perform patch tests c: Contact allergic reaction to plastic, perform patch tests d: Contact allergic reaction to nickel, advise nickel avoidance e: Irritant dermatitis, treat with emollients

Answer 37

d

Question 38

What clinical sign gives the clue to the diagnosis: a: Erythema b: Scaling c: Lichenification d: Cut-off at collar line e: Grey hair indicating advanced age of patient

Answer 38

d (photosensitivity)

Question 39

What pattern of eczema does this patient have: a: Acute b: Pompholyx c: Lichenified d: Infected e: a and b

Answer 39

e

Question 40

What infection does this young child have as a complication of their eczema: a: Fungal – candida b: Staph aureus c: Varicella zoster virus d: Herpes simplex virus e: b and d f: It is acute eczema and may not be infected

Answer 40

e