Dermatitis/Eczema Flashcards
What is Hyperkeratosis?
Increased thickness of keratin layer
What is Parakeratosis?
Persistence of nuclei in the keratin layer
these would usually be lost in the cornification process in the granular layer
What is Acanthosis?
Increased thickness of epidermis
What two things can be seen histologically in a skin biopsy with eczema?
Inflammatory cell infiltrate
Spongiosis
What is spongiosis?
Oedema between keratinocytes
What are inflammatory cell infiltrates?
Acute or chronic
lymphocytes and/or neutrophils
Describe the morphology of the acute phase of eczema
papulovesicular
erthematous (red) lesions
oedema (spongiosis)
ooze or scaling and crusting
Describe the morphology of the chronic phase of eczema
thickening (lichenification)
elevated plaques
Increased scaling
`What 4 concepts are the best descriptors of eczema?
Itchy
ill-defined
erythematous
scaly
Describe the pathogenesis and histological appearance of a Contact Allergic Dermatitis
PATHOGENESIS: Type IV delayed hypersensitivity reaction
HISTOLOGY: spongiotic dermatitis
Describe the pathogenesis and histological appearance of a Contact Irritant Dermatitis
PATHOGENESIS: Trauma e.g. Soap/water
HISTOLOGY: spongiotic dermatitis
Describe the pathogenesis and histological appearance of Atopic eczema
PATHOGENESIS: Genetic and Environmental factors = inflammation
HISTOLOGY: spongiotic dermatitis
Describe the pathogenesis and histological appearance of Drug related eczema
PATHOGENESIS: Type I and Type IV Hypersensitivity Reaction
HISTOLOGY: Spongiotic dermatitis and Eosinophils
Describe the pathogenesis and histological appearance of photo-induced/photosensitive eczema
PATHOGENESIS: Reaction to UV light
HISTOLOGY: spongiotic dermatitis
Describe the pathogenesis and histological appearance of Lichen Simplex
PATHOGENESIS: Physical Trauma to skin e.g. scratching
HISTOLOGY: spongiotic dermatitis and external trauma
Describe the pathogenesis and histological appearance of Stasis Dermatitis
PATHOGENESIS: Physical Trauma to skin e.g. hydrostatic pressure
HISTOLOGY: spongiotic dermatitis and extravasation of RBC’s
What are the most common causes of contact allergic dermatitis?
chemicals
topical therapies
NICKEL
plants
Describe the process of patch testing for a specific allergen
Batteries of allergens are placed in small wells
Applied to back skin
Left in place for 48 hours
Reactions checked at 96 hours
What is a contact irritant dermatitis?
Non-specific physical irritation rather than a specific allergic reaction
Eg Soap/detergent/cleaning products, water, oil
Name clinical features which are often seen in hand dermatitis
Erythema scaling fissuring lichenification nail dystrophy crusting
What type of dermatitis is Nappy Rash?
irritant contact dermatitis to urine
sometimes with ulceration
NOTE: sparing of flexures - unlike in fungal infection
What percentage of school children are affected by atopic eczema?
25%
How can pruritus in atopic eczema affect children of school age?
Leads to sleep disturbance and therefore neurocognitive impairment at school
Describe the typical distribution seen in atopic eczema
Flexural distribution
(inside elbow, back of knee, inside of wrists, front of ankles)
sometimes eyes/neck/genital areas
What other atopic diseases are often associated with eczema?
hayfever
asthma
food allergy
Describe the appearance of atopic eczema in skin of colour
papular
ill defined erythema (often difficult to see)
scaling
extensive lichenification and keloid scarring
What secondary infection is common in atopic eczema
staph aureus
gold crusting
(this easily multiplies on eczema prone skin)
What variation of eczema presents as monomorphic punched out lesions and what virus is it caused by?
Eczema Herpeticum
Caused by Herpes Simplex
What is the diagnostic criteria for atopic eczema in the UK?
Itching plus 3 or more:
- Visible (or Hx of) flexural rash
- Personal history of atopy (or 1st degree relative if under 4)
- Generally dry skin
- Onset before age 2 years
Describe the progression of treatments for eczema
- Plenty of emollients
- Avoid irritants including shower gels and soaps
- Topical steroids
- Treat infection
- Phototherapy – mainly UVB
- Systemic immunosuppressants
- Biologic agents
How does discoid eczema usually present?
Well defined discrete lesions
Patient can often be atopic too
Also can cause secondary infection
How is photosensitive eczema usually noticed?
Cut off at collar
also known as Chronic Actinic Dermatitis
Where does stasis eczema usually present?
The lateral malleolus
What is another word for seborrhoeic dermatitis?
Cradle Cap
What is seborrhoeic dermatitis usually accompanied by?
Fungal infection
What is typical of Pompholyx Eczema?
Sudden onset of Spongiotic vesicles
On lateral aspect of the digits