PATHOLOGY- Inflammatory skin diseases Flashcards
What is the epidermis mainly composed of?
Epithelial cells
Melanocytes
What do epithelial cells do
They make keratin to make keratocytes
List the board categories non infectious inflammatory diseases can fall under
- Dermatitis/ psoriasis
- Blistering
- Connective tissue damage
- Skin lesions as a sign of systemic disease
- Skin lesions caused by metabolic disorders
Name the most common disease of the skin
Eczema/ dermatitis
What does eczema describe
A reaction pattern rather than a specific disease
How common is eczema in children
5% of children in the UK have eczema
What is another name for eczema?
Dermatitis
Name the stages of dermatitis
- Acute dermatitis
- Subacute dermatitis
- Chronic dermatitis
Describe the acute stage of dermatitis
Red skin
Weeping serous exudate
There may be some small vesicles
Describe the subacute phase of dermatitis
Skin is red and crusty
Less exudate
Very very itchy skin
Describe the chronic stage of dermatitis
Skin is thick and leathery
How does eczema look under a microscope during the acute phase?
You’ll see oedemas within the epidermis and fluid filled blisters (spongiosis)
How does eczema look under a microscope during the chronic stage
Epidermis has become thickened and and the normal undulations of the epidermis became quite pronounced
spongiosis is much less
Keratin layer is bigger and thicker
What is spongiosis
Intercellular oedema within the epidermis
Name the different types of of eczema
- Atopic eczema
- Contact irritant dermatitis
- Contact allergic dermatitis
- Dermatitis of unknown aetiology
Who usually has atopic eczema
Children with family history
Often associated with asthma and hay fever
What type of inflammatory disease is atopic eczema
A type 1 hypersensitivity reaction to an allergen
What is contact irritant dermatitis caused by
Direct injury to skin by irritant eg acid, alkali, strong detergent
What is contact allergic dermatitis caused by
Nickel, dyes, rubber
These act as happens which combine with epidermal protein to become immunogenic
What type of inflammatory disease is contact allergic dermatitis?
A delayed type 4 hypersensitivity reaction
What are dermatitis with an unknown aetiology categorised by?
Their morphological subtypes
List the 2 morphological subtypes dermatitis of unknown aetiology can fall under
- Seborrhoeic dermatitis
- Nummular dermatitis
Describe seborrhoeic dermatitis
Dermatitis that affects areas rich in sebaceous glands
EG scalp, forehead, upper chest
Describe nummular dermatitis
Coin shaped lesions
How common is psoriasis
Affects 1-2% of population
Describe how psoriasis looks
- Well defined, red oval plaques on extensor surfaces (knees, elbows, sacrum)
- Fine silvery scale
What happens if you pick at a scale caused by psoriasis (what is this called)
Removal of scale causes small bleeding portitis
This is called Auspitz sign
List some associating symptoms that people may psoriasis may present with
- Pitting nails
- Sero negative arthritis
Describe the appearance of psoriasis under a microscope
- Regular e longed club shaped rete ridges
- Thickening of epidermis over dermal papillae
- Parakeratotic (contains nuclei) scaled
- Collections of neutrophils in scale
What does parakeratoic mean
Contains nuclei
What is the appearance of psoriasis under a microscope called?
Psoriasiform hyperplasia
What do the clinical and microscopic features of psoriasis suggest?
They reflect massive cell turnover
Describe the pathogenesis of psoriasis
Trigger factor leading to a dysfunctional immune reaction
Talk through the aetiology of psoriasis
- Genetic factors
- Environmental trigger factors such as infection, stress, trauma and drugs
Which gene may be responsible for genetic psoriasis
Theres multiple loci on the psoriasis susceptibility or PSORS genes
Many of these loci lie in the region of major histocompatibility complex on chromosome 6p2
Name some diseases that are associated with psoriasis
- Arthropathy (5-10% associated)
- Psychosocial effects
- Cardiovascular disease
- Cancer increased risk of non melanoma skin cancer