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Endo > Lesions > Flashcards

Lesions Flashcards

1
Q

Define primary skin lesion

A

Develops as a direct result of disease processes

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2
Q

Define secondary skin lesions

A

Develop as a consequence of patient’s activities

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3
Q

Compare secondary lesions and secondary pyoderma

A
  • Lesion: due to patient’s actions
  • Pyoderma: bacterial infection which is complicating and underlying skin disease e.g. allergy and demodicosis. Presents with primary lesions e.g. papules and pustules
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4
Q

What may linear lesions indicate?

A

External trauma or lesions associated with blood vessel, dermatome or congenital malformation

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5
Q

What may annular lesions indicat?

A

Peripheral spreading of disease (e.g. pyoderma or dermatophytosis)

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6
Q

What do symmetrical lesions indicate?

A

Systemically mediated disease (often endocrine)

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7
Q

Describe macules

A
  • Primary lesion
  • Circumscribed flat area of change in colour less than 1cm diameter
  • Pigment loss or excess, erythema, haemorrhage
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8
Q

When are erythematous macules often seen?

A

Inflammatory disease of superficial dermis e.g. allergies

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9
Q

What is a patch?

A

Same as a macule but larger than 1cm diameter

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10
Q

What are petechiae?

A

Pinpoint macules caused by haemorrhage

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11
Q

What are ecchymoses?

A

Patches caused by haemorrhage of more than cm diameter

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12
Q

What are cutaneous haemorrhages often indicative of?

A
  • Thrombocytopaenia
  • Defects in coagulation
  • Vasculitis
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13
Q

Describe papules

A
  • Primary lesion
  • Small solid elevation of skin less than 1cm diameter
  • Local accumulation of inflammatory cells
  • Flea allergy dermatitis, canine pyoderma
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14
Q

Describe plaques

A
  • Primary lesions
  • Large elevation of skin, sometimes formed by papules coalescing
  • e.g. eosinophilic plaque in some cats with allergic skin disease
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15
Q

Describe nodules

A
  • Primary lesions
  • Solid elevation of skin greater than 1cm diameter
  • Usually extends into deeper skin layers
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16
Q

What may nodules result from?

A
  • Neoplasia (skin cells, or metastatic)
  • Inflammatory cell accumulation (chronic granulomatous inflammation associateed with infectious or sterile processes)
  • Less commonly, tissue dysplasia or hyperplasia with mineral deposition
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17
Q

What tests are useful in nodular diseases?

A

0 Needle aspiration and cytology

  • Excisional biopsy and histopathology
  • Excisional biopsy and culture
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18
Q

Describe cysts

A
  • Primary lesion

- Cavity with an epithelial lining

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19
Q

Describe tumours

A
  • Primary lesion
  • Large mass involving skin structure
  • Often relates to neoplasia buut can be used in inflammatory disease
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20
Q

Describe pustules

A
  • Primary lesion
  • Small circumscrimbed elevation of epidermis containing pus
  • In dogs usually Staphylococcus intermedius
  • May be a feature of sterile, immune-mediated diseases e.g. pemphigus foliaceus
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21
Q

Describe vesicles

A
  • Primary lesion

- Small circumscribed elevation of epidermis containing clear fluid less than 1cm

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22
Q

Describe bullae

A
  • Primary lesions

- Circumsribed elevation of epidermis containing clear fluid larger than 1cm diameter

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23
Q

Outline some causes of vesicles

A
  • Balloon degeneration of keratinocytes e.g. FMD
  • Loss of cohesion between cells in or just below epidermis due to antibody response directed at proteins in cellular attachment e.g. bullous pemphigoid
  • Cell mediated cytotoxicity leading o a loss of structural integrity of epidermal cells e.g. erythema multiforma
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24
Q

Describe wheals

A
  • Primary lesion
  • Localised mast cell degranulation within skin
  • Urticaria
  • Circumscribed raised lesion consisting of dermal oedema
  • Most common in horses
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25
Q

Give some causes of wheals

A
  • Stings
  • Venoms
  • Insect bits
  • Drug reactions
  • Allergic reactions
  • Physical factors e.g. pressure, cold exercise
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26
Q

Describe scales

A
  • Primary lesion
  • Accumulation of loose cornified fragments of epidermis
  • Ectoparasites and other chronic skin inflammation may lead to scaling
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27
Q

Describe how scaling occurs

A
  • Normally desquamation of cells from stratum corneum occurs so that cells are not seen
  • Accumulation of loose cornified fragments of epidermis
  • Often due to increased epidermal turnover
  • may reflect priamry defects of keratinisation e.g. idiopathic seborrhoea
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28
Q

Describe comedones

A
  • Primary lesion

- Dilated hair follicles devoid of hair and plugged with keratinous debris (blackhead)

29
Q

Describe how comedones form

A
  • Processes interfering with hair growth
  • Induce defects of keratinisation process in follicular infundibulum
  • Most often in dogs
30
Q

What are some differential diagnoses for comedones?

A
  • Demodicosis
  • Endocrine diseases
  • Idiopathic seborrhoea
31
Q

Describe follicular casts

A
  • Primary lesion
  • Accumulation of keratinous debris around hair shaft
  • Seen protruding from follicular ostium or present when hairs plucked and examined
  • Often coexist with comedones
32
Q

Describe crusts

A
  • Primary lesion
  • Dred exudate on skin surface e.g. serum, blood, pus or combination
  • Commonly indiseases with pustular component
33
Q

Describe ulcers

A
  • Secondary lesions

- Break in continuity of epidermis that penetrates the basement membrane

34
Q

Describe erosions

A
  • Secondary lesions

- Incontinuity of epidermis that does not penetrate the basement membrane

35
Q

Describe epidermal collarettes

A
  • Secondary lesions
  • Circular lesion with circular rim of scale or peeling edge
  • Footprint of vesicular or pustular lesion
  • Common lesion type in canine pyoderma
36
Q

Describe scars

A
  • Secondary lesion

- Area of fibrous tissue replacing damaged skin

37
Q

Describe excoriation

A
  • Secondary lesion
  • Erosions or ulceration caused by scratching, biting or rubbing
  • Usually seen as consequence of moderate or severe pruritus
38
Q

Describe fissures

A
  • Secondary lesion
  • Linear split through the epidermis to the underlying dermis
  • Usually seen as consequence of loss of skin elasticity
39
Q

Describe lichenification

A
  • Secondary lesion
  • Accentuation of skin markings giving elephant skin life appearance
  • Associated with chronic inflammation and trauma
  • Usually feature of severe and chronic canine allergic disease or Malassezia infection
  • WHWT and GSD more prone to this
40
Q

List types of pigmentation disturbances

A
  • Hyperpigmentation
  • Hypopigmentation
  • Leukotrichia
41
Q

What is hyperpigmentation?

A

Skin pigmentation increased beyond what is normal for that area

42
Q

What is hypopigmentation?

A

Skin pigmentation decreased beyong what is normal for that area

43
Q

What is leukotrichia?

A

Loss of hair pigment

44
Q

What is skin pigmentation dependent on?

A

Nature and amount of melanin within epidermal cells

45
Q

How does hyperpigmentation often occur?

A
  • Endocrine disease affecting skin

- Consequence of inflammation

46
Q

How does hypopigmentation often occur?

A
  • Inflammatory processes

- Auto-immune diseases centred on dermo-epidermal junction such as lupus erythematosus

47
Q

List potential causes of damage to skin

A
  • Microbial
  • Ectoparasitic
  • Trauma
  • chemical
  • Allergic
  • Autoimmune
  • Endocrine/metabolic
  • Nutritional
  • Environmental
48
Q

List epidermal responses to damage

A
  • Hyperkeratosis
  • Acanthosis
  • Lichenification
  • Vesicle/pustule formation
  • Hyper/hypopigmentation
  • Crusting
  • Alopecia
49
Q

List dermal responses to damage

A
  • Erythema
  • Oedema
  • Thickening
50
Q

What is hyperkeratosis?

A

Increased depth of cornified layer (stratum corneum)

51
Q

What are the different types of scaling?

A
  • Greasy (oleosa)

- Dry (sicca)

52
Q

Describe the formation acanthosis and hyperkeratosis

A
  • Responses to repeated low grade trauma
  • e.g. elbows from lying down
  • Leads to release of cytokines from keratinocytes leading to increased division of basal epidermal cells
  • Fibroblast proliferation, keratinocyte proliferation, affects division of epidermal basal cells
  • Aim is to protect underlying structure
53
Q

Compare acanthosis and hyperkeratosis

A

Acanthosis: increased depth fof epidermis
Hyperkeratosis: increased depth of cornified layer

54
Q

What does lichenification indicate?

A

Chronic disease

55
Q

Describe erythema

A
  • Damage leads to release of pro-inflammatory mediators (incl histamine)
  • Leads to vasodilation of dermal vessles
  • Ultimately leads to erythema
  • Common in infectious and allergic processes
  • Will blanche
56
Q

Describe oedema

A
  • Histamin and other cytokines, increased vascular permeability = leakage of tissue fluid
  • Pit on pressure
  • Classically type I hypersensitivity
57
Q

Describe dermal thickening

A
  • Associated with longer-standing allergic reactions
  • Late phase reaction leading to cellular infiltrate
  • Chronic inflammatory conditions
  • Sometimes nodular
58
Q

Describe alopecia

A
  • Loss of hair (partial/complete)

- Failure to grow or damage

59
Q

What may lead to failure of hair to grow leading to alopecia?

A
  • Endocrine disorders (often bilateral)
  • e.g. testicular tumour leading to increased oestrogen
  • Nutritional
60
Q

Give examples of ways hair follicles may be damaged leading to alopecia

A
  • Bacterial pyoderma

- Dermatophytosis (ringworm)

61
Q

How may different disease elicit similar cellular or tissue responses/signs?

A
  • Signs seen by affecting particular parts of skin
  • Set ways in which those parts can respond
  • Thus multiple diseases can affect these areas and have similar effects
62
Q

Discuss the causes of secondary hyperkeratosis

A
  • Non-specific sign
  • Increased turnover of epidermis or imbalance between turnover and desquamation
  • Metabolic, infectious, parasitic, immune mediated, neoplastic
  • Leishmaniasis (protozoal disease), chroic hepatic disease (systemic metabolic disease) and dermatophytosis (fungal infection) for example
63
Q

Discuss the causes of vesicle formation

A
  • Vesicules usually with viruses (e.g. foot and mouth) or autoimmune disease
  • Auto-antibodies attack intercellular proteins leading to separation of keratinocytes
64
Q

Discuss the causes of pustule formation

A
  • Pustules associated with infection (e.g. bacterial pyoderma Staphylococcus pseudintermedius)
  • Can also be sterile e.g. autoimmune diseases such as Pemphigus foliaceus
65
Q

Discuss the causes of crusting

A
  • Caused by mulitple exudative and ulcerative disease
  • Physical damage (mechanical, thermal, chemical)
  • Infectious processes (viral, bacterial, fungal and parasitic)
  • Sterile inflammatory diseases (autoimmune)
  • Ulcerating neoplasms
66
Q

Discuss the causes of erythema

A
  • Infectious and allergic processes

- Some neoplastic processes e.g. epitheliotropic lymphoma

67
Q

Discuss the possible causes of oedema

A
  • Type I hypersensitivity
  • Pressure and exercise in horses
  • Mast cell tumour may lead to histamin release and thus urticaria
68
Q

List further diagnostic tests for the investigation of skin lesions

A
  • Skin scrapes
  • Trichograms
  • Cytology
  • FNA
  • Biopsy
  • Microbial culture
  • Wood’s lamp examination
69
Q

Why are further diagnostic tests required in most cases with skin lesions?

A
  • Many diseases will cause similar symptoms
  • Required in order to make correct diagnosis and thus provide correct treatment
  • Require signalment, history and diagnostic tests

Endo (30 decks)

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