Skin pathology Flashcards

1
Q

What are the layers of the epidermis?

A
  • statum corneum
  • stratum spinocum
  • stratum basale
  • basement membrane below these
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2
Q

What does the dermis contain?

A
  • vessels
  • collagen
  • nerves
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3
Q

What is adnexa?

A
  • hair follicles
  • sweat glands
  • sebaceous glands
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4
Q

What are examples of epidermal responses to injury?

A
  • hyperkeratosis
  • epidermal hyperplasia
  • malassezia
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5
Q

What is hyperkeratosis?

A
  • =increased thickness of the stratum corneum
  • very common feature of longstanding surface trauma
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6
Q

What are the clinical signs of hyperkeratosis?

A
  • dry flaky skin
  • scales
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7
Q

What are the diseases/conditions characterised by hyperkeratosis?

A
  • any chronic surface injury
  • seborrhea
  • zinc deficiency
  • endocrinopathies
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8
Q

What is this animal presenting?

A
  • severe hyperkeratosis
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9
Q

What condition is this?

A
  • hyperkeratosis due to zinc deficiency
  • very thick layer (epidermis)
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10
Q

What disease does this calf have?

A
  • congenital ichtyosis (fish skin disease)
  • hairless skin
  • thickened and scaly
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11
Q

What is epidermal hyperplasia?

A
  • increased numbers (therefore layers) of keratinocytes in the epidermis
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12
Q

What is Acanthosis?

A
  • specific term that refers to increase thickness of the stratum granulosm
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13
Q

What is the earliest reaction to skin injury?

A
  • epidermal hyperplasia
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14
Q

What condition is this showing? What are the signs?

A
  • epidermal hyperplasia
    • see mild hyperkeratosis
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15
Q

What condition does this dog have?

A
  • long standing duration epidermal hyperplasia = alopecia
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16
Q

What condition is shown here?

A
  • malassezia
  • keratinocytes
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17
Q

In what circumstances can epidermal hyperplasia occur?

A
  • occurs in hypersensitivity disorders (allergy)
  • e.g. flea bite reactions
  • recruits eosinophils and mast cells
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18
Q

What skin condition is shown here?

A
  • lichenification (severe epidermal hyperplasia)
  • thickened and leathery skin = exaggeration of the normal skin markings resulting from longstanding surface trauma or friction
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19
Q

What is this and where does it normally occur?

A
  • callus =thickened often pigmented and hyperkeratotic plaque
  • hyperkeratosis and hyperplasia at the same time
  • tends to occur at pressure points such as elbow/ chronic licking/ rubbing
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20
Q

What are vesicles and bullae and what are the causes?

A
  • = fluid filled cavities within or beneath the epidermis (blister)
  • causes
    • frictional trauma
    • autoimmune diseases (targeting IC juntions between keratinocytes)
    • burns
    • viral diseases (FMD)
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21
Q

What is the difference between vesicles and bullae?

A
  • vesicle = <1cm
  • bullae = >1cm
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22
Q

What is shown here?

A
  • vesicle and bullae
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23
Q

What is shown by the star?

A
  • sub-epidermal vesicle due to thermal burn
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24
Q

What are examples of vesicular diseases? and how do vesicles form?

A
  • FMD
  • vesicular stomatitis
  • vesicular exanthema
  • swine vesicular disease
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25
Q

What is a pustule and what are the causes?

A
  • vesicle containing pus (=degenerate neutrophils, inflammatory cells)
  • causes:
    • autoimmune diseases (e.g. pemphigus)
    • bacterial infections (e.g. staphylococcal infection = superficial pyoderma)
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26
Q

What is this?

A
  • pustule
  • contained within epidermis
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27
Q

What is shown here?

A
  • pustule
  • pemphigus foliceus subcorneal pustule
28
Q

What may erosions and ulcers be the result of? and what do they imply?

A
  • result of:
    • mechanical trauma (e.g. pruritus)
    • infectious
    • inflammation
    • neoplasia
    • thermal burns
    • ischaemia
    • chemical damage
    • radiation
  • Imply
    • some degree of necrosis of the ep cells in epidermis
29
Q

What are these?

A
  • if there is bleeding - damage is underneath the BM (no vessels in the epidermis) = ulcer
30
Q

Is this more likely to be an ulcer or erosion? Why?

A
  • ulcer
  • bleeding
  • lesion has crossed BM
31
Q

What is this showing?

A
  • erosion/ ulceration
  • have loss of epidermis and exposure of dermis
32
Q

What is a crust?

A
  • =consolidated, dessicated, surface exudate that contains keratin, serum, cellular debris (from inflam cells and/ or keratinocytes), variable rbcs (haemorrhage) and often microorganisms
  • often the end result is loss of integrity of epidermis
33
Q

WHat is this?

A
  • crust
  • (partially replaces epidermis)
34
Q

What does this slide show?

A
  • crust
35
Q

How does crust form?

A
36
Q

What is Neoplasia?

A
  • neoplasia in the epidermis can only arise from epithelial cells (keratinocytes)
    • benign = papilloma (wart)
    • malignant = carcinoma (usually squamous)
37
Q

Causes of neoplasia?

A
  • often spontaneous
  • viral infections (e.g. papillomavirus)
  • chronic sunlight exposure (white coated animals)
38
Q

WHat is this showing?

A
  • papilloma
39
Q

What is this showing?

A
  • squamous cell carcinoma
  • neoplastic cells invade the underlying dermis and form accumulations of keratin
40
Q

What is this cat presenting with?

A
  • squamous cell carcinoma (SCC)
  • ep cells invading tissue underneath
41
Q

What is atrophy? (dermal response to injury)

A
  • = decrease in the mass of a tissue (skin) due to decreased size/ number of its cells (after its reached its normal size)
  • in the dermis = decreased quantity of collagen fibrils; clinically thin, translucent skin, with prominent vasculature
42
Q

What are the causes of atrophy?

A
  • malnutrition
  • endocrinopathies (e.g. hypothyroidism, Cushings)
43
Q

What is this showing and why?

A
  • atrophy of collagen
  • adnexa go into atrophy
44
Q

What is inflam of the dermis called?

A
  • dermatitis
  • inflam cells are present in the dermis (lymphocytes, plasma cells, neutrophils, macrophages, eosinophils)
45
Q

What are these?

A
46
Q

What are the causes of dermatitis?

A
  • infectious (bacteria, viruses, parasites)
    • bacteria attract neutrophils and macrophages
    • viruses attract lymphocytes and plasma cells
    • parasites attracts eosinophils
  • autoimmune or immune-mediated
    • lymphoplsmacytic inflam
  • allergic
    • eosinophili inflam
47
Q

What is erythema?

A
  • reddening of the skin
  • due to increased blood supply to the area and vasodilation
  • associated with acute inflam
48
Q

What is eosinophilic dermatitis associated with?

A
  • parasite infection
  • allergy-type reaction
  • collagen necrosis
  • degeneration
49
Q

What is this condition?

A
  • feline miliary dermatitis
  • crusts, ulcers/ erosion/ erythema
50
Q

What is this animal presenting with?

A
  • cat, flea-allergy dermatitis
    • hair loss
    • redness
    • hyperaemia
    • inflam cells in dermis
51
Q

What is this dog presenting with?

A
  • flea allergy
  • erythema and alopecia
52
Q

What kind of dermatitis is this?

A
  • eosinophilic dermatitis
  • flea allergy
  • more nuclei
  • lots of inflam cells
  • oedema in dermis
53
Q

What is the hallmark of granulomatous/ pyogranulomatous dermatitis?

A
  • mycobacterium spp.
  • main inflam cell = macrophage
54
Q

What inflam is this?

A
  • granulomatous inflam
  • lots of macrophages
  • few neutrophils
55
Q

What is this? and what is it caused by?

A
  • feline leprosy
  • caused by mycobacteria
56
Q

What is this?

A
  • Leishmania
57
Q

What is lymphoplasmacytic inflam caused by?

A
  • chronic infections in general
  • diseases characterised by lymphocyte and plasma cells infiltrates:
    • viral infections
    • autoimmune and immune-mediated diseases
58
Q

What type of lymphoplasmacytic inflam is this? and what species does it affect?

A
  • discoid erythematosus
  • uncommon
  • dogs and horses
59
Q

What type of dermatitis is this showing?

A
  • interface dermititis (obscuring the BM)
60
Q

What is neutrophilic inflam associated with?

A
  • bacterial infection (either primary or secondary)
  • can form discrete abcesses
  • common in the dermis associated with:
    • rupture of hair follicles
    • penetrating injury
61
Q

What is this?

A
  • subcutaneous abscess
  • (dermis, subcutis and pushing on muscle)
62
Q

What is this?

A
  • neoplasia - benign cutaneous histiocytoma
  • seen in young dogs
63
Q

label this

A
64
Q

Where do the main adnexal diseases occur?

A
  • in hair follicle
65
Q

What is folliculitis/ furunculosis?

A
  • folliculitis- inflam of hair follicle
  • furunculosis - inflam of the hair follicle + rupture
66
Q

What causes folliculitis and furunculosis?

A
  • almost always infectious:
    • staphylococcus sp
    • demodex sp (mange)
    • dermatophytes (ringworm)
67
Q

Describe the evolution of folliculitis?

A