Immune 5 - Inflammatory Dermatoses Flashcards
What lies between the epidermis and dermis in skin?
The basement membrane
Langerhans cells?
APCs
Merkel cells?
Involved in sensation
Describe how keratinocytes differentiate as they go from deep to superficial
Basal cell –> prickle cell —> granular cell —> keratin
Where are keratinocytes located?
In the stratum corneum
Describe the structure of the stratum corneum
Lipids between the corneocytes act as a “glue” to hold it together.
These lipids are very important for skin function - defects may lead to eczema
Name a gene mutation common in eczema patients
Filagrin
Describe atopic eczema
Atopy = tendency to develop hypersensitivity
Atopic diseases = eczema, asthma, hay fever
Atopic eczema = common, relapsing and remitting
Caused. by defective barrier function in the skin
Describe the order of disease acquisition according to the atopic march
- Eczema
- Food allergy
- Asthma
- Rhinitis
If acute atopic eczema shifts to chronic atopic eczema, how does the immune response change
Acute - activation of CD4+ lymphocytes and Th2 immune response
Chronic - activation of CD4+ and CD8+ lymphocytes and Th1 immune response
Describe one of the signs of having filagrin gene mutation
palmar hyperlinearity
Eczema with lichenfication occur in?
Chronic eczema
Due to persistent rubbing
What is erythrodermic eczema
Systemic eczema and patient is generally unwell - patient should be treated in hospital
What bacteria is associated with eczema?
S. aureus
Give an example of a viral infection that has invaded during eczema
Eczema herpeticum
Eczema allows herpes simplex to spread widely
Name different types of eczema
- Seborrhoeic - yeast overgrowth. Greasy scale (e.g. dandruff) - treated with topical steroids / antifungals
- Allergic contact dermatitis - allergy to a specific thing - having atopic eczema predisposes to allergic contact dermatitis
- Discoid - disc shapes scattered around the body (elderly/overwash)
Describe psoriasis
Skin lesions - salmon-pink plaques, well defined
Pathogenesis (requires genetic susceptibility) - trigger required (e.g. alcohol/stress/smoking, etc) –> immune response occurs causing psoriasis
T cells in dermis release cytokines (particularly TNF-a) –> neutrophils enter epidermis —> overproduction of keratinocytes –> causes thickening of epidermis
Describe the histological features of psoriasis
- Hyperkeratinosis
- Parakeratosis
- Acanthosis
- Inflammation
- Dilated blood vessels
Distinguish psoriasis soles and athletes foot
Fungal infections - usually asymmetrical whereas psoriasis can be symmetrical
Psoriasis occurs in places of trauma/pressure
What are some signs of nail psoriasis
- Subungual hyperkeratosis
- Dystophic nail and loss of cuticle
- Pitting
- Onycholysis (nail has lifted away from nailbed)
Psoriasis affects most/all nails, fungal infection only a couple of nails
Describe guttate psoriasis
Raindrop, papule-like psoriasis (often on back)
May occur after fungal/streptococcal infection
What form of psoriasis occurs on palms?
Palmoplantar pustolosis - smoking predisposes
Describe generalised pustular psoriasis
Loads of white psoriatic papules everywhere
Patient may come in with host of other problems e.g. malaise, tachycardia etc
Needs to go hospital to get treated
What 3 things cause pus
- Bacterial / viral infection
- Psoriasis
- Drug reaction
Acne is a disorder of the ….. unit
Pilosebaceous
Describe acne formation
genetic + hormonal factors
- Comedone formation - hyperkeratinisation of neck of follicle
- Increased sebum production
- Overgrowth of bacteria - propionibacteria acnes
- Inflammatory cells and debris spill out into dermis - triggers even more inflammation
Difference between whitehead and blackhead?
Whitehead - comedone, looks like covered with skin
Blackhead - comedone open, can see dead keratin within
Papule = small inflammatory lesion
Acne consists of papules, closed comedones (whiteheads) and open comedones (blackheads)
Describe bullous pemphigoid
Autoimmune condition, occurring in elderly
Autoantibody against component of basement membrane (between epidermis and dermis)
Epidermis - derived from ectoderm - anchored by tonofilaments (to BM)
Dermis - derived from mesoderm - anchored by anchoring fibrils (to BM)
Antigens that are targeted are BPAg1 and BPAg2
Describe epidermolysis bullosa
If its not antibodies that are attacking the proteins, but a genetic defect in proteins - you get epidermolysis bullosa
Describe the pathology of bullous pemphigoid
Sub-epidermal blister occurs
Presents with multiple tense, firm, itchy blisters
Describe pemphigus vulgaris
Auto-antibodies against desmosomes (which connect keratinocytes together in the epidermis)
Autoantibodies split above the basement membrane (within epidermis - creating a meshwork)
Treatment = oral steroids, oral immunosuppressants
