5: Pathology of rashes Flashcards

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1
Q

Name five functions of the skin.

A

Physical barrier

Thermoregulation

Maintains fluid / electrolyte balance

Vitamin D synthesis

UV protection

Immune surveillance

Sensory functions (touch, pressure, vibration etc.)

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2
Q

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

A

Keratinised stratified squamous epithelium / keratinocytes

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3
Q

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

A

Melanocytes

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4
Q

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

A

Eccrine glands

Sebaceous glands too

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5
Q

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

A

1 : 10

melanocytes : basal cells

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6
Q

What do cells in the granular layer possess?

A

Keratohyalin granules

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7
Q

What joins cells in the prickle cell layer?

A

Desmosomes

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8
Q

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

A

Dendritic projections

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9
Q

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

A

dendritic , antigens

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10
Q

Where are melanocytes found?

A

Basal layer only

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11
Q

Where are Langerhans cells found?

A

In both the upper and lower epidermis

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12
Q

Which elastic fibre makes up a lot of the dermis?

A

Collagen

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13
Q

Which property of collagen makes it ideal for the dermis?

A

Elastic

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14
Q

What are the two divisions of the dermis?

A

Papillary dermis

Reticular dermis

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15
Q

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

A

Reticular dermis

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16
Q

How do melanocytes look under the microscope?

A

Pale pink

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17
Q

What is hyperkeratosis?

A

Thickening of the keratin layer

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18
Q

Tumours which penetrate the basement membrane are prone to ___.

A

metastasise

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19
Q

What is parakeratosis?

A

Persistence of nuclei in the keratin layer

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20
Q

What is acanthosis?

A

Increased thickness of epithelium

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21
Q

What is papillomatosis?

A

Irregular thickening of the epithelium - pointy, jagged basal layer

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22
Q

What is spongiosis?

A

Oedema of spaces in the epidermis

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

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23
Q

Which inflammatory cells appear in the epidermis during eczema?

A

Lymphocytes

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24
Q

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

A

Langerhans cells

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25
Q

What are the four main types of inflammatory skin disease?

A

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

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26
Q

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

A

Psoriasis

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27
Q

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

A

Koebner phenomenon

28
Q

What is the pathogenesis of psoriasis?

A

Epidermal hyperplasia

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

29
Q

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

A

Neutrophils

Complement

30
Q

Which cells are found in high numbers in psoriatic plaques?

A

Neutrophils

31
Q

On which particular surfaces can psoriasis be found?

A

Scalp

EXTENSOR surfaces of elbows

Lower back

Knees

32
Q

What is erythema?

A

Redness of the skin caused by increased blood flow during inflammation

33
Q

What is erythroderma?

A

Intense and widespread erythema during to inflammatory skin disease

34
Q

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

A

Fluid balance

35
Q

What is seen in the basal layer in psoriasis?

A

Thickening - irregular and pointy “pegs”

36
Q

What can be seen in the keratin layer in psoriasis?

A

Hyperkeratosis + loads of neutrophils

37
Q

What is damaged in lichenoid disorders?

A

Basal layer

38
Q

Give an example of a lichenoid disorder.

A

Lichen planus

Discoid lupus

39
Q

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

A

Sawtooth appearance

40
Q

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

A

Lymphocytes

41
Q

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

A

Necrotic keratinocytes

42
Q

What does lichen planus look like on the skin?

A

Discrete groups of red, itchy papules

43
Q

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

A

Buccal mucosa

White, streaky appearance

44
Q

Why might a person develop vesicles and bullae?

A

Eczema

Herpes simplex infection

Burns

45
Q

Give three examples of vesiculobullous skin diseases.

A

Pemphigus

Pemphigoid

Dermatitis herpetiformis

46
Q

What is the main feature of a vesiculobullous disease?

A

Blisters

47
Q

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

A

Coeliac disease (gluten intolerance)

48
Q

What is pemphigus?

A

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

49
Q

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

A

IgG

desmosomes connecting keratinocytes in the basal layer of the epidermis

50
Q

Which enzymes digest desmosomes in pemphigus vulgaris?

A

Proteases

51
Q

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

A

Acantholysis

52
Q

What is acantholysis?

A

Loss of intercellular connections i.e the desmosomes joining keratinocytes

53
Q

Why isn’t the basal layer destroyed in pemphigus?

A

Hemidesmosomes connect cells in the basal layer

These connections aren’t targeted by IgG

54
Q

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

A

Bullous pemphigoid

55
Q

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

A

IgG

56
Q

Why do blisters form in bullous pemphigoid?

A

Epidermis slides off basement membrane and the space fills with fluid

57
Q

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

A

Dermatitis herpetiformis

58
Q

Where is dermatitis herpetiformis usually found?

A

Elbows, knees and buttocks

59
Q

What forms in the papillary dermis in dermatitis herpetiformis?

A

Microabscesses

60
Q

Which gastrointestinal disease is dermatitis herpetiformis CLOSELY associated with?

A

Coeliac disease

61
Q

Which antibody is involved in dermatitis herpetiformis?

A

IgA

62
Q

Why does acne occur?

A

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

63
Q

Which hormone is closely associated with acne?

A

CRH → Androgens

64
Q

The blockage of what is usually associated with acne?

A

Pilosebaceous units

65
Q

What is rosacea?

A

Recurrent facial flushing (“butterfly rash”), usually found in females

+/- pustules and rhinophyma

66
Q

What are some known triggers for rosacea?

A

Sunlight

Alcohol

Spicy food

Stress