Dermatitis

Question 1

What is dermatitis?

Answer 1

• Also known as eczema

* A group of inflammatory skin disorders

Question 2

What are the classifications of dermatitis?

Answer 2

○ Endogenous
	- Atopic eczema 
	- Seborrhoeic eczema
	- Discoid eczema
	- Chronic hand/ foot eczema
	- Venous ("gravitational") eczema
	- Asteatotic eczema
	- Lichen simplex/ nodular prurigo 
○ Exogenous 
	- Irritant contact eczema 
	- Allergic contact eczema

Question 3

Describe the inflammation in dermatitis

Answer 3

○ Erythema and surface change (dryness and scaling)

○ Itch which may be intolerable (ranges from mild to intolerable)

Question 4

Describe acute dermatitis

Answer 4

○ Tiny vesicles or larger bullae
○ Oedematous inflamed skin
○ Scratching leads to serosanguinous exudate and crust

Question 5

Describe subacute dermatitis

Answer 5

○ Less oedema

○ Some flaking and scaling

Question 6

Describe chronic dermatitis

Answer 6

○ Thickened and dry

○ Prominent skin creases (lichenification)

Question 7

What happens if a secondary bacterial infection occurs?

Answer 7

○ Crusts
○ Papules
○ Pustules

Question 8

Describe the histology of dermatitis

Answer 8

○ Acute: Keratinocytes are swollen with increased intracellular fluid
○ Chronic: little oedema but prominent thickening of the epidermis (acanthosis) and scaling (hyperkeratosis)
○ All: Inflammatory cells present around the upper dermal vessels

Question 9

Explain atopic eczema (briefly)

Answer 9

• Usually starts under the age of 2
• Often associated with other atopic diseases
• Genetically complex familial disease with strong maternal influence

Question 10

Explain the pathophysiology of atopic eczema

Answer 10

○ Not exactly known
○ Abnormalities in skin barrier function
○ Abnormalities in adaptive and innate immunity
○ Loss of function mutations in the epidermal barrier protein Filaggrin cause ichthyosis vulgaris
○ Filaggrin deficiency
- Poor barrier function
- Dry skin
- Allows antigen penetration into epidermis

Question 11

What are the exacerbating factors of atopic eczema?

Answer 11

○ Infection (in the skin or systemically)
○ Lack of infection (in infancy) may cause the immune system to follow the T2 pathway and allow eczema to develop
○ Soap, bubble bath and woollen fabric can irritate the skin
○ Teething in young children
○ Severe anxiety or stress can in some individuals
○ Cat and dog dander
○ Delayed food hypersensitivity

Question 12

What are the clinical features of atopic eczema?

Answer 12

○ Itchy, erythematous, scaly skin patches, especially in flexures of ankles, knees, elbows and wrists and around the neck
○ Infants: eczema starts on cheeks before spreading around the body
○ Very acute lesions: weep or exudate and can show small vesicles

Question 13

What are the associated features of atopic eczema?

Answer 13

○ Skin of upper arms and thighs may feel roughened due to follicular hyperkeratosis
○ Palms may show very prominent skin creases
○ Dry fish-like scaling of the skin, which is non-inflammatory and often prominent on the lower legs

Question 14

What are the complications of atopic eczema?

Answer 14

○ Broken skin can become secondarily infected by bacteria
○ Cutaneous viral infections may be more widespread
○ Ocular complications
- Conjunctival irritations
- Keratoconjunctivitis
- Cataracts

Question 15

What are the investigations for atopic eczema?

Answer 15

○ History

○ Clinical features

Question 16

What is the prognosis of atopic eczema?

Answer 16

Most will spontaneously clear

Question 17

What is the management of atopic eczema?

Answer 17

○ Avoid irritants
○ Manipulating diet 
○ Topical therapies 
	- Steroids
	- Calcineurin inhibitors 
○ Antibiotics 
	- Flucloxacillin (550 mg 4 times a day)
○ Sedating antihistamines 
○ Bandaging
○ Second line agents
	- UV phototherapy
	- Ciclosporin
	- Azathioprine 
	- Methotrexate
	- Oral prednisolone 
○ New drugs
	- Anti-IL-4/IL-13 monoclonal antibody dupilumab 
	- Omalizumab

Question 18

What are the clinical features of seborrhoeic eczema?

Answer 18

○ Occurs in greasy areas of the body
○ On the face: scaling and erythema around the nose, medial eyebrows, hairline and ear canals
○ Scalp: dandruff (mild), more severe can look like psoriasis
○ Pre-sternal area in men
○ Large flexures
○ Ano-genital area
○ Self-limiting infantile form: scalp scaling/ crackle cap and a non-itchy napkin dermatitis

Question 19

What is the management for seborrhoeic eczema?

Answer 19

○ Usually runs a chronic course with relapses
○ Treatment is suppressive rather than curative
○ Topical azole antifungal creams
○ Short term use of mild-moderate potency steroids
○ Topical calcineurin inhibitors (TCIs)
○ Ketoconazole shampoo

Question 20

Explain venous eczema

Answer 20

• Usually affects the elderly and those with varicose veins or a history of venous thrombosis
• Inner calf is involved
• Coexists with signs of venous hypertension
○ Hemosiderin deposition
○ Lipodermatosclerosis
○ Varicose ulceration
• May be complicated by allergic contact dermatitis

Question 21

What is the management of venous eczema?

Answer 21

○ Bland emollients
- Liquid paraffin and soft white paraffin mix
○ Short term use of a mildly potent topical steroid
○ Manage underlying venous hypertension

Question 22

Explain discoid eczema

Answer 22

• Well dermatated, inflamed, scaly patches, sometimes with tiny vesicles
• Usually affects limbs and torso
• Immensely itchy
• Potent topical steroid usually required to clear individual lesions

Question 23

Explain hand eczema

Answer 23

• Causes
○ Contact dermatitis/ eczema: due to external harsh substance or allergy provoking substance
○ Endogenous dermatitis/ eczema: no external factors can be identified (there may also be involvement of the feet)
• Clinical features
○ In the finger webs and backs of hands
○ Dry, sore chapped skin
○ Extremely common in cold dry weather and those who wash their hands frequently
• Can be part of atopic eczema
• Hyperkeratotic form
○ Dry scaly plaques and cracks on the palms and soles
• Patch testing should be used on anyone with chronic hand eczema to investigate contact allergies

Question 24

Explain allergic contact and irritant contact eczema

Answer 24

• Delayed type hypersensitivity reaction
• Rash does not appear until 12-24 hour after skin contact
• Management
○ Minimising contact with allergens
○ Managing eczema actively
○ The oral retinoid, alitretinoin

Question 25

Explain lichen simplex

Answer 25

• Chronic form of eczema
• Skin is thickened and lined in response to repeated rubbing or scratching
• Management
○ Topical antipruritics
○ Short term treatment with a potent topical steroid
○ Advice about habit reversal

Question 26

Explain nodular purigo

Answer 26

• Very persistent
• Itchy, nodular eruption
• Perpetuated by picking and scratching
• May develop on background atopic eczema
• Scattered, eroded and hyperkeratotic nodules are typically found on the upper trunk and the extensor surfaces of limbs
• Management (only gives temporarily relief)
○ Topical steroids
○ Sedating antihistamines
○ Antipruritics
• Diagnosis
○ Exclusion of other pathologies