Dermatitis + Atopic Eczema Flashcards
Define hyperkeratosis
Hyperkeratosis = increased thickness of keratin layer
Define parakeratosis
Parakeratosis = persistence of nuclei in the keratin layer
Define acanthosis
Acanthosis = increased thickness of epidermis
Define papillomatosis
Papillomatosis = irregular epithelial thickening
Define spongiosis
Spongiosis = oedema between keratinocytes
Define inflammatory cell infiltrate
Inflammatory cell infiltrate = acute or chronic lymphocytes and/or neutrophils
Give seven types of dermatitis
- Contact allergic
- Contact irritant
- Atopic
- Drug-related
- Photo-induced or photosensitive
- Lichen simplex
- Stasis dermatitis
Contact allergic dermatitis
- Pathogenesis?
- Histology?
Delayed type 4 hypersensitivity reaction
Spongiotic dermatitis
Contact irritant dermatitis
- Pathogenesis?
- Histology?
Trauma e.g. soap, water
Spongiotic dermatitis
Atopic dermatitis
- Pathogenesis
- Histology?
Genetic + environmental factors resulting in inflammation
Spongiotic dermatitis
Drug-related dermatitis
- Pathogenesis
- Histology?
Type I or IV hypersensitivity reaction
Spongiotic dermatitis + eosinophils
Photo-induced or photosensitive dermatitis
- Pathogenesis
- Histology?
Reaction to UV light
Spongiotic dermatitis
Lichen simplex dermatitis
- Pathogenesis
- Histology?
Physical trauma to the skin e.g. scratching
Spongiotic dermatitis + external trauma
Stasis dermatitis
- Pathogenesis
- Histology?
Physical trauma to the skin - hydrostatic pressure
Spongiotic dermatitis + extravasation of RBCs
Define contact allergy
Specific or non-specific?
Contact allergy – something has to come into contact to the skin which develops a delayed type hypersensitivity reaction. This is SPECIFIC.
Define contact irritant
Contact irritant – non-specific reaction to something that is lightly traumatising the skin e.g. soap and water.
How can drug related dermatitis be confirmed on histology?
Presence of eosinophils
Contact allergic dermatitis
- Name some allergens
Very common in response to chemicals, topical therapies, nickel (most common), plants, latex, perfumes etc.
What is irritant (contact) dermatitis?
- Name some common irritants
This is non-specific physical irritation rather than a specific allergic reaction.
E.g. soap/detergent/cleaning products, water, oil - may be difficult to distinguish from allergic contact dermatitis – e.g. using cleaning product with fragrance in it may be allergic irritant, or both.
Give some common clinical features of atopic eczema
- Pruritus
- Ill-defined erythema & scaling
- Generalised dry skin
- Flexural distribution (varies with age)
- Associated with other atopic diseases, e.g. asthma, allergic rhinitis, food allergy
Give three chronic changes in atopic eczema.
What does crusting indicate?
- Lichenification
- Excoriation – means breaking of the skin surface by external trauma
- Secondary infection – most commonly staph aureus in eczema
Crusting indicates staph aureus infection.
Monomorphic punched out lesions = ?
Eczema herpeticum casued by herpes simplex virus
What are some treatment options for atopic eczema?
- Plenty of emollients*
- Avoid irritants including shower gels and soaps
- Topical steroids*
- Treat infection
- Phototherapy – mainly UVB
- Systemic immunosuppressants
- (Biologic agents)
Discoid eczema
- Symptoms?
- Associated with?
Shows a well-defined erythema and scale.
These patients are often atopic too.
