Immune 5 - Inflammatory Dermatoses

Question 1

What lies between the epidermis and dermis in skin?

Answer 1

The basement membrane

Question 2

Langerhans cells?

Answer 2

APCs

Question 3

Merkel cells?

Answer 3

Involved in sensation

Question 4

Describe how keratinocytes differentiate as they go from deep to superficial

Answer 4

Basal cell –> prickle cell —> granular cell —> keratin

Question 5

Where are keratinocytes located?

Answer 5

In the stratum corneum

Question 6

Describe the structure of the stratum corneum

Answer 6

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

Question 7

Name a gene mutation common in eczema patients

Answer 7

Filagrin

Question 8

Describe atopic eczema

Atopy = tendency to develop hypersensitivity

Atopic diseases = eczema, asthma, hay fever

Answer 8

Atopic eczema = common, relapsing and remitting

Caused. by defective barrier function in the skin

Question 9

Describe the order of disease acquisition according to the atopic march

Answer 9

1. Eczema
2. Food allergy
3. Asthma
4. Rhinitis

Question 10

If acute atopic eczema shifts to chronic atopic eczema, how does the immune response change

Answer 10

Acute - activation of CD4+ lymphocytes and Th2 immune response

Chronic - activation of CD4+ and CD8+ lymphocytes and Th1 immune response

Question 11

Describe one of the signs of having filagrin gene mutation

Answer 11

palmar hyperlinearity

Question 12

Eczema with lichenfication occur in?

Answer 12

Chronic eczema

Due to persistent rubbing

Question 13

What is erythrodermic eczema

Answer 13

Systemic eczema and patient is generally unwell - patient should be treated in hospital

Question 14

What bacteria is associated with eczema?

Answer 14

S. aureus

Question 15

Give an example of a viral infection that has invaded during eczema

Answer 15

Eczema herpeticum

Eczema allows herpes simplex to spread widely

Question 16

Name different types of eczema

Answer 16

1. Seborrhoeic - yeast overgrowth. Greasy scale (e.g. dandruff) - treated with topical steroids / antifungals
2. Allergic contact dermatitis - allergy to a specific thing - having atopic eczema predisposes to allergic contact dermatitis
3. Discoid - disc shapes scattered around the body (elderly/overwash)

Question 17

Describe psoriasis

Answer 17

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

Question 18

Describe the histological features of psoriasis

Answer 18

1. Hyperkeratinosis
2. Parakeratosis
3. Acanthosis
4. Inflammation
5. Dilated blood vessels

Question 19

Distinguish psoriasis soles and athletes foot

Answer 19

Fungal infections - usually asymmetrical whereas psoriasis can be symmetrical

Psoriasis occurs in places of trauma/pressure

Question 20

What are some signs of nail psoriasis

Answer 20

1. Subungual hyperkeratosis
2. Dystophic nail and loss of cuticle
3. Pitting
4. Onycholysis (nail has lifted away from nailbed)

Psoriasis affects most/all nails, fungal infection only a couple of nails

Question 21

Describe guttate psoriasis

Answer 21

Raindrop, papule-like psoriasis (often on back)

May occur after fungal/streptococcal infection

Question 22

What form of psoriasis occurs on palms?

Answer 22

Palmoplantar pustolosis - smoking predisposes

Question 23

Describe generalised pustular psoriasis

Answer 23

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

Question 24

What 3 things cause pus

Answer 24

1. Bacterial / viral infection
2. Psoriasis
3. Drug reaction

Question 25

Acne is a disorder of the ….. unit

Answer 25

Pilosebaceous

Question 26

Describe acne formation

genetic + hormonal factors

Answer 26

1. Comedone formation - hyperkeratinisation of neck of follicle
2. Increased sebum production
3. Overgrowth of bacteria - propionibacteria acnes
4. Inflammatory cells and debris spill out into dermis - triggers even more inflammation

Question 27

Difference between whitehead and blackhead?

Answer 27

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)

Question 28

Describe bullous pemphigoid

Answer 28

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

Question 29

Describe epidermolysis bullosa

Answer 29

If its not antibodies that are attacking the proteins, but a genetic defect in proteins - you get epidermolysis bullosa

Question 30

Describe the pathology of bullous pemphigoid

Answer 30

Sub-epidermal blister occurs

Presents with multiple tense, firm, itchy blisters

Question 31

Describe pemphigus vulgaris

Answer 31

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