Inflammatory dermatoses Flashcards
State the two layers of the dermis
papillary dermis (above) reticular dermis (below)
What structures may be found in the dermis?
apocrine glands
sebaceous glands
hair follicle
What are some important cells found in the stratum basale?
merkel cells (involved in sensation), melanocytes, dividing keratinocytes.
Describe the keratinocyte differentiation pathway
basal cell => prickle cell => granular cell => keratin
What is the stratum corneum composed of? Why is it important?
Defects lead to?
- Composed of corneocytes (differentiated keratinocytes) with lipids in between each of them; dead keratinocytes are on the surface
- Very important barrier function of the skin.
- Defects lead to eczema.
Define atopy.
List the main atopic diseases.
Atopy – tendency to develop hypersensitivity
Atopic diseases - eczema, asthma, hayfever
What kind of disease is atopic eczema?
- very common itchy skin condition with onset from first 6 months of life
- relapsing and remitting
- many grow out of it
Describe the aetiology of eczema
Defective barrier of skin which allows entry of irritants, allergens and pathogens which then cause inflammation.
State the gene mutation that is common in eczema patients. What does this gene normally encode for?
Filaggrin gene mutation
a filament-associated protein that binds to keratin in epithelial cells
What is a clinical sign of the filaggrin gene mutation?
Palmar hyperlinearity
Use a word describe the appearance of chronic eczema
Lichenification (skin becomes thick and leathery); usually a result of constant scratching or rubbing.
What is eczema herpeticum caused by?
Viral infection (usually with HSV)
State three other types of eczema
Seborrhoeic eczema
Allergic contact dermatitis
Discoid eczema
What kind of skin condition is seborrhoeic eczema?
What is it associated with?
Common skin condition affecting babies and adults but is NOT itchy.
Associated with an overgrowth of malassezia (species of yeast on the skin that causes inflammation).1
Describe the distinctive bodily distribution of seborrhoeic eczema
nasolabial folds, eyebrows, scalp, central chest, axilla and groin.
Discoid eczema appears as
small discrete discs.
Psoriasis is a common inflammatory dermatoses usually starting when?
How does it look like?
common inflammatory dermatoses usually starting in teens or 40s/50s.
raised, red, scaly patches on the skin
Types of psoriasis:
- Chronic plaque
- Guttate psoriasis
- Palmoplantar pustulosis.
- Generalised pustular psoriasis (same as palmoplantar pustulosis, just everywhere)
What factors are involved in the aetiology of psoriasis?
Triggers for the condition include…?
- Genetic susceptibility; many genes are implicated including PSOR1
- Environmental factors
Triggers include infections, drugs and stress
Describe the pathophysiology of psoriasis?
T-lymphocytes move out of blood vessels into the dermis and initiate release of cytokines (e.g. TNFa). The epidermis thickens in response (produces more keratinocytes). Neutrophils infiltrate the epidermis and lymphocytes infiltrate the dermis forming pustules
Describe what Nail psoriasis may look like?
Onycholysis (separation of nail from its nail bed)
Pitting of the nail
Histology of psoriasis
Hyperkeratosis Parakeratosis Acanthosis Inflammation Dilated blood vessels
What kind of disease is acne?
Disease of the pilosebaceous unit of the skin.
Describe the steps in the pathogenesis of acne
- Hyperkeratinisation of the epidermis in the infundibulum of hair follicles.
- Accumulation of dead keratinocytes in the lumen of the hair follicle.
- Increase sebum production stimulated by androgens.
- Proliferation of Propionibacterium acnes within pilosebaceous unit.
- Rupture of inflamed pilosebaceous unit à further inflammation of surrounding skin.
