5: Pathology of rashes

Question 1

Name five functions of the skin.

Answer 1

Physical barrier

Thermoregulation

Maintains fluid / electrolyte balance

Vitamin D synthesis

UV protection

Immune surveillance

Sensory functions (touch, pressure, vibration etc.)

Question 2

The epidermis is primarily made up of which kind of cell?

Answer 2

Keratinised stratified squamous epithelium / keratinocytes

Question 3

Which cells are responsible for pigmentation and can be found at the dermo-epidermal junction?

Answer 3

Melanocytes

Question 4

Which type of gland secretes onto the skin’s surface?

Answer 4

Eccrine glands

Sebaceous glands too

Question 5

What is the ratio of melanocytes to basal cells in the epidermis?

Answer 5

1 : 10

melanocytes : basal cells

Question 6

What do cells in the granular layer possess?

Answer 6

Keratohyalin granules

Question 7

What joins cells in the prickle cell layer?

Answer 7

Desmosomes

Question 8

What property of melanocytes allows them to transfer synthesised pigment to keratinocytes?

Answer 8

Dendritic projections

Question 9

Langerhans cells are another example of ___ cells and monitor the epidermis for ___.

Answer 9

dendritic , antigens

Question 10

Where are melanocytes found?

Answer 10

Basal layer only

Question 11

Where are Langerhans cells found?

Answer 11

In both the upper and lower epidermis

Question 12

Which elastic fibre makes up a lot of the dermis?

Answer 12

Collagen

Question 13

Which property of collagen makes it ideal for the dermis?

Answer 13

Elastic

Question 14

What are the two divisions of the dermis?

Answer 14

Papillary dermis

Reticular dermis

Question 15

Which layer of the dermis contains appendages such as hair and glands?

Answer 15

Reticular dermis

Question 16

How do melanocytes look under the microscope?

Answer 16

Pale pink

Question 17

What is hyperkeratosis?

Answer 17

Thickening of the keratin layer

Question 18

Tumours which penetrate the basement membrane are prone to ___.

Answer 18

metastasise

Question 19

What is parakeratosis?

Answer 19

Persistence of nuclei in the keratin layer

Question 20

What is acanthosis?

Answer 20

Increased thickness of epithelium

Question 21

What is papillomatosis?

Answer 21

Irregular thickening of the epithelium - pointy, jagged basal layer

Question 22

What is spongiosis?

Answer 22

Oedema of spaces in the epidermis

NOT neccessarily causing blisters - spongiotic diseases are not the same as vesiculobullous diseases

Question 23

Which inflammatory cells appear in the epidermis during eczema?

Answer 23

Lymphocytes

Question 24

Which cells signal for lymphocytes to infiltrate the epidermis in eczema?

Answer 24

Langerhans cells

Question 25

What are the **four** main types of inflammatory skin disease?

Answer 25

**Spongiotic** - intraepidermal odema - e.g eczema **Psoriasiform** - extension of rete ridges - e.g psoriasis **Lichenoid** - basal layer damage - e.g lichen planus, lupus **Vesiculobullous** - blistering - e.g pemphigus, pemphigoid, dermatitis herpetiformis

Question 26

Which chronic inflammatory skin disease is found in 3% of people worldwide?

Answer 26

**Psoriasis**

Question 27

Which phenomenon describes the onset of psoriasis at sites of trauma for unknown reasons?

Answer 27

**Koebner phenomenon**

Question 28

What is the pathogenesis of psoriasis?

Answer 28

**Epidermal hyperplasia** leading to increased cell turnover and thickening of the keratin layer to form scaly plaques

Question 29

**Munro micro abscesses** are a useful sign of psoriasis. What inflammatory cell is responsible and which immune component signals them to the site?

Answer 29

**Neutrophils** **Complement**

Question 30

Which cells are found in high numbers in psoriatic plaques?

Answer 30

**Neutrophils**

Question 31

On which particular surfaces can psoriasis be found?

Answer 31

**Scalp** **EXTENSOR surfaces of elbows** **Lower back** **Knees**

Question 32

What is **erythema**?

Answer 32

**Redness of the skin** caused by increased blood flow during inflammation

Question 33

What is **erythroderma**?

Answer 33

**Intense** and **widespread** **erythema** during to inflammatory skin disease

Question 34

What must be monitored in any patient with weepy or oozing skin disease e.g erythroderma?

Answer 34

**Fluid balance**

Question 35

What is seen in the **basal layer** in psoriasis?

Answer 35

**Thickening** - irregular and pointy "pegs"

Question 36

What can be seen in the **keratin layer** in psoriasis?

Answer 36

**Hyperkeratosis** + **loads of neutrophils**

Question 37

What is damaged in **lichenoid disorders**?

Answer 37

**Basal layer**

Question 38

Give an example of a **lichenoid disorder**.

Answer 38

**Lichen planus** **Discoid lupus**

Question 39

What sort of appearance does the basal layer have in lichenoid disorders?

Answer 39

**Sawtooth appearance**

Question 40

Which inflammatory cells can be found in the basal layer in lichenoid disorders?

Answer 40

**Lymphocytes**

Question 41

Which dying cells, found in the basal layer, characterise lichenoid disorders?

Answer 41

**Necrotic keratinocytes**

Question 42

What does lichen planus look like on the skin?

Answer 42

Discrete groups of red, itchy papules

Question 43

Apart from the skin, where else can lichen planus be found? What does it look like?

Answer 43

**Buccal mucosa** **White, streaky appearance**

Question 44

Why might a person develop vesicles and bullae?

Answer 44

**Eczema** **Herpes simplex infection** **Burns**

Question 45

Give **three** examples of vesiculobullous skin diseases.

Answer 45

**Pemphigus** **Pemphigoid** **Dermatitis herpetiformis**

Question 46

What is the main feature of a vesiculobullous disease?

Answer 46

**Blisters**

Question 47

What do patients with **dermatitis herpetiformis** tend to have in addition?

Answer 47

**Coeliac disease** (gluten intolerance)

Question 48

What is **pemphigus**?

Answer 48

**Rare autoimmune disease** in which the epidermal layer loses its integrity and **blisters form**

Question 49

In pemphigus vulgaris, the body creates ___ antibodies against desmoglein 3 - what does this protein maintain?

Answer 49

**IgG** **desmosomes** connecting keratinocytes in the basal layer of the epidermis

Question 50

Which enzymes digest desmosomes in pemphigus vulgaris?

Answer 50

**Proteases**

Question 51

Which process is caused by the digestion of desmosomal attachments by proteases in pemphigus vulgaris?

Answer 51

**Acantholysis**

Question 52

What is **acantholysis**?

Answer 52

**Loss of intercellular connections** i.e the desmosomes joining keratinocytes

Question 53

Why isn't the **basal layer** destroyed in pemphigus?

Answer 53

**Hemi**desmosomes connect cells in the basal layer These connections aren't targeted by IgG

Question 54

In which disease is the **basal** **layer** disrupted in a similar manner to that of the **prickle cell layer** in **pemphigus vulgaris**?

Answer 54

**Bullous pemphigoid**

Question 55

Which antibodies are responsible for desmosome destruction in **pemphigus** and **pemphigoid**?

Answer 55

**IgG**

Question 56

Why do blisters form in bullous pemphigoid?

Answer 56

**Epidermis slides off basement membrane and the space fills with fluid**

Question 57

Which vesiculobullous disease presents as intensely itchy red lesions on the elbows, knees and buttocks?

Answer 57

**Dermatitis herpetiformis**

Question 58

Where is dermatitis herpetiformis usually found?

Answer 58

**Elbows, knees and buttocks**

Question 59

What forms in the **papillary dermis** in dermatitis herpetiformis?

Answer 59

**Microabscesses**

Question 60

Which gastrointestinal disease is **dermatitis herpetiformis** CLOSELY associated with?

Answer 60

**Coeliac disease**

Question 61

Which **antibody** is involved in dermatitis herpetiformis?

Answer 61

**IgA**

Question 62

Why does **acne** occur?

Answer 62

**Blocking of sebaceous glands by keratin** and **infection by anaerobic bacteria** (e.g ***Corynebacterium spp.***)

Question 63

Which hormone is closely associated with acne?

Answer 63

**CRH → Androgens**

Question 64

The blockage of what is usually associated with acne?

Answer 64

**Pilosebaceous units**

Question 65

What is **rosacea**?

Answer 65

**Recurrent facial flushing** ("butterfly rash"), usually found in females +/- pustules and rhinophyma

Question 66

What are some known **triggers** for rosacea?

Answer 66

**Sunlight** **Alcohol** **Spicy food** **Stress**