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PathY5 > Skin pathology > Flashcards

Skin pathology Flashcards

1
Q

What condition is this?

A

Bullous Pemphigoid

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2
Q

What is the most common cancer in the Western World?

A

Basal Cell Carcinoma

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3
Q

Does BCC metastasise?

A

Does not metastasise, but can cause large disfigurement as it occurs in areas exposed to the Sun

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4
Q

Which is the largest organ in the human body?

A

Skin

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5
Q

What are the functions of the skin?

A

Protection:
Þ Essential barrier between external environment and internal body
Þ Protects against mechanical, chemical, osmotic, thermal and
UV damage and microbial invasion

Metabolic
Þ Role in vitamin D synthesis
Þ Body temperature regulation

Sensation
Þ Sensory organ for touch, temperature, pain and other
stimuli

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6
Q

What are the 3 layers of the skin?

A

Epidermis
Dermis
Hypodermis

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7
Q

What is the epidermis?

A

Outermost layer

Formed by layers of keratinocytes undergoing terminal maturation

This involved increased keratin production and migration towards external surface – known as cornification

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8
Q

What are the cells of the epidermis?

A

Keratinocytes

Melanocytes (melanin production and pigment formation)

Langerhans cells (antigenpresenting dendritic cells)

Merkel cells (sensory mechanoreceptors)

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9
Q

What are the layers of the epidermis?

A

Divided into layers deep to superficial:
stratum basale
stratum spinosum
stratum granulosum
stratum lucidum
stratum corneum

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10
Q

How long do keratinocytes travel?

A

Keratinocytes travel from stratum basale to corneum in 30-40 days

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11
Q

What is the dermis?

A

Tightly connected to epidermis via dermo-epidermal junction

Consists of two layers: superficial papillary layer and deeper reticular layer

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12
Q

What is contained in the dermis?

A

Contains fibroblasts (synthesise ECM), mast cells, blood vessels, cutaneous sensory nerves and skin appendages (e.g. hair follicles, nails, sebaceous and sweat glands)

Pilosebaceous unit: Sebaceous glands release their glandular secretions into the hair follicle shaft. The hair follicle is associated with an arrector pili muscle which contract to cause the follicle to stand upright.

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13
Q

What is the hypodermis?

A

Subcutaneous tissue: Major body store of adipose tissue

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14
Q

How thick is skin (3 layers)?

A

6mm

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15
Q

What is the main function of the epidermis?

A

The epithelial cells that line your skin and
mucous membranes allow body fluids to come
out (e.g. sweat and sebum)

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16
Q

Summarise the dermis

A

o Supporting structure
o Made up of collagen and elastic fibres
o Contains blood vessels, sweat glands, sebaceous
glands, hair follicles and nerve fibres

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17
Q

Which part of the body has the most sebaceous glands?

A

Nose

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18
Q

Which part of the body has no hairs?

A

Palms and soles

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19
Q

How does skin change with age?

A

o Much thinner epidermis
o More fragile dermis – poorer quality collagen and
elastic bundles
§ Hence elderly bruise easier

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20
Q

Which part of the skin is involved in the inflammatory reaction pattern?

A

epidermis

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21
Q

What are the different types of inflammatory reaction pattern?

A

o Vesiculobullous: forms bullae
o Spongiotic: becomes oedematous
o Psoriasiform: becomes thickened
o Lichenoid: forms a sheeny plaque
o Vasculitic: associated with vasculitides
o Granulomatous: associated with granulomas

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22
Q

What are the vesiculobullous conditions?

A

Bullous pemphigoid
Pemphigus vulgaris
Pemphigus foliaceus

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23
Q

What is bullous pemphigoid?

A

Blistering condition in which you get IgG antibodies produced against BPAg1/2 –
these are protein components of the basement membrane between epidermis and dermis

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24
Q

What type of reaction is bullous pemphigoid?

A

Type II antibody-dependent hypersensitivity reaction

Autoimmune disorder driven by IgG and C3 which attack the basement membrane

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25
Q

Does BP kill?

A

High morbidity rate, particularly in elderly

10-20% mortality so must be recognised

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26
Q

How does BP present?

A

Present with tense blisters called bullae, particularly in flexor regions
§ The blisters tend to be a bit more robust than in pemphigus vulgaris as they are due to a deeper inflammation in the skin

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27
Q

What is the histology of BP?

A

§ Characteristic pattern

§ Complement is activated and it starts to attack the way in which keratinocytes sit on basement membrane

§ Lots of eosinophils are recruited releasing elastase

§ Result: damage to anchoring proteins that anchor the lower keratinocytes onto the basement membrane

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28
Q

What are the other causes of tense bullae?

A

bullae e.g. drug reaction -> hence an immunofluorescence stain looking for IgG and C3 can be done to help diagnosis -> forms band under immunofluorescence along basement membrane zone

This can be done directly on specimen or indirectly using serum

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29
Q

What is pemphigus vulgaris?

A

o Blistering condition in which IgG antibodies are produced against desmoglein 1 and 3 which are essential cement proteins in the epidermis (anti-epithelial cell cement
protein antibody)
o As a result, keratinocytes split away from each other (acantholysis)
o Blisters are thin and weak and easily rupture

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30
Q

What’s the histology of PV?

A

Damage occurring within the keratinocyte layers
§ There is acantholysis (loss of intercellular connections leading to loss of cohesion between keratinocytes)

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31
Q

How can immunofluorescence be used in PV?

A

Immunofluorescence can be done to see IgG around the affected individual keratinocytes

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32
Q

What is pemphigus foliaceus?

A

o Rare
o Bullae are rarely seen intact as they are so thin that they often come off -> leaves an excoriated looking area
o IgG mediated
o Affects stratum corneum (top layer)
o Immunofluorescence can be used

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33
Q

Do you remember the house analogy?

A

o Think of it as a house with a solid foundation (basement membrane)

o The house is made of bricks (keratinocytes) that are joined together by cement

o The house has a roof (keratin layer on the surface)

o In bullous pemphigoid, all the damage is occurring between the lowest layer of bricks and the concrete foundation

o The house becomes lifted off the basement membrane and the space gets filled with fluid

o Bullous pemphigoid: bottom floor
o Pemphigus vulgaris: first floor
o Pemphigus foliaceus: roof

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34
Q

What are the spongiotic diseases?

A

Discoid eczema
Contact dermatitis

35
Q

What are the characteristics of discoid eczema?

A

o Atopic
o Producing white plaques in flexor regions
o Very itchy
o Can become very extensive and look
erythematous throughout body

36
Q

What are the characteristics of contact dermatitis?

A

Due to latex gloves but can also occur from nickel, watch
straps etc

37
Q

What is the histology of spongiotic diseases?

A

o Spongiosis means that there is oedema (fluid between the adjacent keratinocytes)
o Scratching at top -> showing hyperparakeratosis (thickening of the skin on the surface where you have been scratching)
o T cell mediated, and eosinophils recruited here too

38
Q

What is a differential for an eczematous reaction pattern?

A

Drug reaction

39
Q

What are the characteristic features of plaque psoriasis?

A

Classic example of psoriasiform: classic silvery plaques

This occurs on extensor surfaces e.g. knuckles, elbows, knees

There are other variants of psoriasis but this is the classic presentation

Munro’s micro-abscesses: classically seen,
sit at top of epidermis, accumulations of
neutrophils

Dilated vessels also seen

40
Q

What is the histology of plaque psoriasis?

A

Skin is constantly shredding – the normal time for a stem cell to form a matured keratinocyte is ~56 days
In psoriasis, shredding occurs rapidly -> 7 days rather than 56

Many normal layers of epidermis are lost e.g. granular cell layer
(stratum granulosum) – as there is not enough time to form it

Epidermis is thickened as it is proliferating so rapidly – layer of
parakeratosis at the top

41
Q

What are the characteristics of lichen planus?

A

o Typically present with itchy, redpurple plaques on extensor distal surfaces e.g. wrist, as well as classical white lines in their mouth (Wickam striae)
o Note: dermatologists always look inside mouth to assess buccal mucosa
o T-cell mediated

42
Q

What is the histology of lichen planus?

A
  1. Lots of T cells
  2. Band like inflammation between dermis and epidermis (unclear margin)

§ Lots of T lymphocytes
§ Bottom layer of keratinocytes damaged (apoptosis) -> leads to band-like inflammation in between epidermis and dermis; unable to see where dermis finishes and epidermis starts
§ Second image is lower power image of same thing – you can see a band-like lymphocytic infiltrate just under the epidermis
§ This can be seen in lichen planus and also in mycosis fungoides

43
Q

Characterise pyoderma gangrenosum

A
  • This is an example of a lesion that does NOT fit into one of the categories
  • This is a common manifestation of many different underlying systemic diseases e.g. sclerosing cholangitis, hepatitis, IBD, leukaemia
  • Sometimes patients present with skin lesion due to an underlying nondermatological condition -> must do further investigations and take a complete history
44
Q

What are the characteristics of sebhorrheic keratosis?

A
  • Common benign lesion
  • Looks like a pigmented cauliflower-like lesion
  • Completely harmless
45
Q

What is the histology of sebhorrheic keratosis?

A

o Proliferating epidermis in an orderly fashion

o As it is orderly, it is likely benign (disorderly is a sign of dysplasia, malignancy)

o Horn cysts seen: entrapped keratin surrounded by a proliferating epidermis

46
Q

What are the characteristics of a sebaceous cysts?

A
  • Central puncture, smooth, round, circumscribed, non-mobile
  • Can get infected, inflamed, and rupture
  • Epidermis has invaginated into dermis
  • Benign
  • Can be very smelly, especially if rupture
47
Q

What are the characteristics of BCC?

A

• Typically occurs in sun-exposed areas in elderly
• Rolled pearly edge, central area of ulceration, telangiectasia
• Also called rodent ulcer -> can look like this following
extensive ulceration
• Surgery involves reconstruction – can be challenging

48
Q

What is the difference between Cancer and dysplasia?

A

§ Epithelial cancer (e.g. breast, skin, prostate)
involves issue with the epithelial cells. In skin,
keratinocytes (epidermis) sit on the
basement membrane -> as soon as any
of these break through the basement
membrane and enter underlying mucosa
(in skin, dermis) then it is CANCER
rather than just dysplasia, as it now has
the potential to metastasise e.g. via
nerve, blood vesse

49
Q

Do BCC metastasize?

A

Basal cell carcinomas do not metastasise – they
are locally invasive

50
Q

What is Bowen’s Disease?

A

• Squamous cell carcinoma in situ
• Large keratin horn
o This is not cancer – it is pre-cancerous
• It is key to find the lesion before it becomes malignant

51
Q

What is the histology of Bowen’s disease?

A

Keratinocytes are still within the epidermis, but
they are behaving differently -> larger,
pleiomorphic, hyperchromatic, odd mitotic figures
(disorganised growth pattern)

52
Q

Is Bowen’s disease neoplasia?

A

No, it is dysplasia. Dysplasia is divided into 1, 2 and 3 depending on grade level. Grade 3 (high grade) have high likelihood of turning into cancer if left alone

53
Q

What is the difference between poorly differentiated and well differentiated?

A

o Poorly differentiated means cells are beginning to
look less like the tissue they originate from;
second diagram; cannot tell what kind of cancer it
is as none of the underlying phenotype present any
longer; worse prognosis
o Well differentiated = still looks like epidermis

54
Q

What is the precursor for SCC?

A

Bowen’s Disease

55
Q

What causes greater risk of recurrence?

A

Tumours can wrap themselves around nerve (perineural
invasion) – 3rd diagram
o Recurrence is greater in these cases -> monitored
more strongly post-op

56
Q

What causes naevi?

A

Melanocytes are normally scattered on the
basal layer of the epidermis -> produce naevi
when they start to accumulate and proliferate

57
Q

What is an intradermal naevus?

A

nest of melanocytes within the dermis

58
Q

What is a compound naevus?

A

nest within the epidermis and dermis

59
Q

What is a junctional naevus?

A

group of
melanocytes creating nests in the
epidermis, typically occur in younger
population

60
Q

Can normal melanocytes be in the dermis?

A

Normal melanocytes can be present in dermis (unlike keratinocytes)
– this is NOT malignancy
As melanocytes mature, they drop from epidermis to dermis

61
Q

What are characteristics of MM?

A

o Irregular outline
o Variable pigmentation
o Bleeding
o Itchy
o Growing
o These are all worrying signs

62
Q

What does ABCDE stand for in MM?

A

o Asymmetry
o Border irregularity
o Colours
o Diameter
o Evolution

63
Q

What causes MM?

A

o Melanocytes are abnormally
moving up through the epidermis
(upward migration/pagetoid spread)
o Bigger melanocytes than normal

64
Q

What is the histology of MM in dermis?

A

Normally melanocytes get smaller as they mature and move into dermis
§ Here, they are the same size at the top and bottom and are mitotically active (replicate)
§ Usually, should not see mitotic components in melanocytic lesion in dermis as it is a sign of it being a malignant melanoma EXCEPT in pregnancy
§ Once the cells go into the dermis, become mitotically active and lack the ability to mature, then you get a diagnosis of malignant melanoma

65
Q

How do you stage MM?

A

Staging of MM is based on depth (millimetres) – Breslow thickness
o A melanoma with a thickness of >4mm has a very high mortality (>50%)

66
Q

Can you have skin mets?

A

Yes:
o Small papule that looks fairly benign
o This turned out to be metastatic renal cell
carcinoma

67
Q

Lichen planus are which type of inflammatory
reaction pattern?

A

Lichenoid

68
Q

Where in the epidermis does the bullae in pemphigus vulgaris form?

A

Between the
keratinocytes (intraepidermal)

69
Q

Where in the epidermis does the bullae in
bullous pemphigoid form?

A

subepidermal

70
Q

White silvery plaques on extensor surfaces are seen in which condition?

A

Psoriasis

71
Q

Breslow thickness is used to stage which skin cancer?

A

Malignant melanoma

72
Q

Which common skin cancer does NOT metastasise?

A

Basal cell carcinoma

73
Q

What condition is this?

A

Pemphigus Vulgaris

74
Q

What condition is this?

A

Pemphigus Foliacus

75
Q

What condition is this and what type of inflammatory disorder is it part of?

A

Discoid Eczema

Spongiotic Disease

76
Q

What condition is this?

A

Contact Dermatitis

77
Q

What condition is this?

A

Plaque psoriasis

78
Q

What condition is this?

A

Lichen planus

79
Q

What condition is this?

A

Pyoderma Gangrenosum

80
Q

What condition is this?

A

Sebhorreic Keratosis

81
Q

What condition is this?

A

Sebaceous cyst

82
Q

Label A, B, C and D

A

A. MM

B. BCC

C. SCC

D. Bowen’s Disease

83
Q

What are these?

A
  1. Benign Junctional Naevus
  2. Compound Naevus

PathY5 (98 decks)

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