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Year 3 > Dermatopathology > Flashcards

Dermatopathology Flashcards

1
Q

During embryology, what does the neural tube become?

A

CNS

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2
Q

What does the notochord induce during embryology?

A

Formation of the neural tube

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3
Q

The notochord forms from which kind of cells?

A

Mesoderm cells

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4
Q

What are the 5 layers of the epidermis?

A 
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale
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5
Q

What are the 3 stages of the hair cycle?

A

Anagen: active stage of hair growth
Catagen: hair stops growing but is not shed
Telogen: follicle recedes and hair falls out

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6
Q

What is acantholysis?

A

Loss of keratinocytes cohesion

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7
Q

What is acanthosis?

A

Increased thickness of stratum spinosum (often used to indicate epidermal hyperplasia)

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8
Q

What is alopecia?

A

Hair loss or failure to grow

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9
Q

What is atopy?

A

Allergic skin disease

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10
Q

What is meant by ballooning degeneration?

A

Intracellular oedema

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11
Q

What is a bullae?

A

Collection of fluid >1cm in diameter

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12
Q

What is folliculitis?

A

Luminal, mural or peri-follicular inflammation of the hair follicle

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13
Q

What is furunculosis?

A

Perifollicular inflammation due to hair follicle wall rupture (dermal pyogranulomatous inflammation)

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14
Q

What is hyperkeratosis?

A

Increased thickness of the keratin layer, with (parakeratotic) or without (orthokeratotic) nuclei

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15
Q

What is a pustule?

A

Cavitation of the epidermis filled with inflammatory cells

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16
Q

What is pigmentary incontinence?

A

Melanin granules and melanophages within the dermis

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17
Q

What is seborrhea?

A

Increased scale formation, with (S. oleosa) or without (S. sicca) excessive greasiness

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18
Q

What is spongiosis?

A

Epidermal intercellular oedema

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19
Q

What is a vesicle?

A

Fluid-filled blister

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20
Q

What is greasy pig disease caused by?

A

Staphylococcus hyicus

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21
Q

Skin lesions can be classified based on which 4 things?

A

Lesion type (eg bulla, pustule)
Distribution
Aetiological agents
Underlying pathogenetic mechanism (eg inflammatory)

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22
Q

What causes ‘diamond’ skin lesions in pigs?

A

Erysipelothrix infection (bacteria)

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23
Q

A neutrophilic vasculitis is suggestive of what?

A

A type III hypersensitivity reaction or septicaemia

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24
Q

A lymphoplasmacytic vasculitis is suggestive of what?

A

Cell-mediated immune-response

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25
Q

What is eosinophilic vasculitis suggestive of?

A

Type I hypersensitivity reaction, or other eosinophil-dominated dermatoses (eg eosinophilic granuloma)

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26
Q

Describe impetigo

A

Superficial pustular dermatitis with NO involvement of the hair follicle
Erythematous papule -> pustules (composed mainly of neutrophils)

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27
Q

Describe greasy pig disease

A

Acute superficial exudative pyoderma of young (5-35 days old) pigs
Caused by Staphylococcus hyicus
Exotoxin produces cleavage between stratum layers
Greasy dark brown exudate over eyes, snout, chin, ears
3 clinical forms: peracute (rapid spread to body -> death), acute, subacute (lesions confined to head, more surviving piglets)
Bacterial colonies

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28
Q

Describe dermatophilosis

A

Acute to chronic exudative superficial dermatitis caused by Dermatophilus congolensis (gram + coccoid bacteria -> branching filaments)
Wet skin and skin trauma are favourable
Thick parakeratotic crusts (continuous epidermal invasion)

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29
Q

Describe deep pyoderma

A

Staphylococcus spp=most commonly involved bacteria
Follicular papula -> pustule -> crusts, coalescing ulcers, alopecia -> epidermal acanthosis (increased thickness of S.spinosum)
Histology: neutrophilic folliculitis and furunculosis, bacterial colonies -> free keratin fragments -> foreign body reaction and haemorrhages

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30
Q

Herpes viruses have which kind of inclusion bodies?

A

Intranuclear

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31
Q

Pox viruses have which kind of inclusion bodies?

A

Intracytoplasmic

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32
Q

Define poxviruses

A

DNA viruses with high epitheliotropism
Some have zoonotic potential
Capable of causing vesicular and proliferative lesions

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33
Q

Describe cowpox

A

Affects cats
Single lesions on face or forepaws
Ulcers -> papules and pustules
Histology: focal, sharply demarcated ulcer, covered with fibrinonecrotic exudate

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34
Q

Describe orf

A

Affects kids and lambs
High morbidity but low mortality
Affects lip commissure -> lips and muzzle -> legs (rarely)
Multifocal to coalescing raised and flat grey crusts
Histology: ballooning degeneration and spongiosis (intra- and intercellular oedema) with epidermal hyperplasia and crust formation
Zoonotic

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35
Q

Describe sheep pox

A

> 50% mortality
Africa, Asia, Middle East
Cutaneous lesions are the expression of systemic disease (resp and GI systems)
Distribution: disseminated, esp. in sparsely wooled areas
Vesicles -> crusty pustules, papules -> dermal oedema
Histology: vesicles, pustules and papules due to vacuolar degeneration of S. spinosum, eosinophilic intracytoplasmic inclusion bodies (also within macrophages)

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36
Q

Describe swinepox

A

Negligible mortality
Distribution: ventrolateral abdomen, medial legs and lateral thorax
Erythematous papules -> pustules
Histology: ballooning degeneration, spongiosus (intra- and intercellular oedema), pustules, inclusion bodies, crust formation

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37
Q

Describe herpes virus dermatitis

A

Cats: felid herpes virus type I (FeHV-1)
Common pathogen of upper airways, but skin lesions often occur in absence of resp. signs
Primarily on nasal planum and haired skin of face
Persistent/recurrent crusts, ulcers and vesicles
Histology: ulcerative and necrotising dermatitis, large intranuclear glassy inclusion bodies and mixed dermal infiltration

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38
Q

Describe Malassezia dermatitis

A

Caused by the yeast Malassezia pachydermatis
Cats, dogs
Predisposing factors probably required (eg skin allergies)
Face, ears, ventral neck, axilla, medial legs
Erythema, alopecia, greasiness, lichenification (leathery skin), hyperpigmentation
Histology: parakeratotic (with nuclei) hyperkeratosis, epidermal hyperplasia, spongiosis. Mixed cell exocytosis. Aggregates of yeasts within crusts or S.corneum
Intensive pruritis

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39
Q

What is the causal agent of Malassezia dermatitis?

A

Yeast: Malassezia pachydermatis

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40
Q

Describe dermatophytosis

A

Superficial mycotic infection (ringworm), confined to the keratin layer of skin, claws, hair
Three main genera: Microsporum, Trichophytoa and Epidermophytoa
Favourable conditions: microabrasions/maceration of S.corneum in moist skin, prolonged corticosteroid treatment, immune deficiencies
Transmission: infected hair and keratin fragments. Fungi migrate to follicular lumen, proliferate along follicle
Circular expanding areas of scaling and alopecia. Often furunculosis and chronic pyogranulomas develop (kerion) and mimic tumours
Histology: ortho- and parakeratosis and acanthosis (increased thickness of S.spinosum). Luminal folliculitis, furunculosis and pyogranulomas

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41
Q

What is a fistula?

A

Draining tract

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42
Q

What is a mycetoma?

A

Tumour-like lesion characterised by tumefaction, draining tracts (fistula) and grains in the discharge

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43
Q

What are the 2 orders of Zygomycosis?

A

Mucorales (angioinvasion and dissemination)

Entomophthorales (local subcutaneous granulomas)

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44
Q

Describe zygomycosis

A

Two orders: Mucorales and Entomophthorales
Caused by contaminated wounds and penetrating objects
Non-contagious
Trunk, neck, head
Solitary large ulcerated nodules with serosanguinous exudate and scattered yellow-white gritty masses (kunker)
Histology: thin-walled, occasionally septate and uncommonly branching hyphae within necrotic lesions surrounded by multifocal to diffuse eosinophilic and granulomatous inflammation

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45
Q

Describe Besnoitiosis

A

Caused by Besnoitia spp
Two host life cycle: Definitive=cat. Intermediate=variable, mainly cattle and horses
Causes large intracellular cysts in intermediate host species

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46
Q

Describe Leishmania

A

Obligate intracellular apicomplexan parasite of macrophages
Transmitted by blood-sucking sandflies
Two clinical forms:
Alopecic: stronger Th1 response, fewer parasites
Nodular: predominant Th2 response, more parasites
Head, limbs, dorsal midline
Gross lesion description: nodules, alopecia, ulcers or pustules
Histology: hyperkeratotic, nodular to diffuse superficial and deep granulomatous dermatitis, variably dominated by plasma cells

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47
Q

What is myiasis?

A

The infestation of living tissues by the larval stages (maggots) of dipterous flies

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48
Q

What causes Sarcoptic mange?

A

Sarcoptes scabiei

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49
Q

Describe sarcoptic mange

A

Caused by Sarcoptes scabiei
Zoonotic, highly contagious, notifiable
Extremely pruritic
Pigs and dogs
Inner surface of pinna, spreading to head, neck, legs
Life cycle is within tunnel burrowed under S.corneum -> scales and crusts
Histology: severe acanthosis (increased thickness of S.spinosum), ortho- and patchy parakeratosis, spongiosis, leukocyte exocytosis and eosinophilic pustules

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50
Q

Describe demodectic mange

A

Demodex mites are obligate parasites, life cycle is within the lumen of hair follicles and adnexa
Dogs
Alopecia, scaling and comedones in the squamous form; pustules, folliculitis and furunculosis in pustular form (with bacteria)
Localised form: well-circumscribed self-limiting lesions on ears, lips, eyes and extremities
Generalised form: diffuse alopecia and scaling on face and legs
Histology: severe suppurative folliculitis and furunculosis

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51
Q

What is a bruise?

A

The local effect of vigorous pressure (blunt trauma) can cause the occurrence of acute intradermal and/or subcutaneous haemorrhages

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52
Q

During the healing process of a bruise, what causes the bruises typical red colour to fade?

A

Erythrocyte removal (recruited leukocytes and phagocytes) and haemoglobin catabolism (haemoglobin red -> biliverdin green -> bilirubin yellow)

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53
Q

What is the difference between hypersensitivity and autoimmunity?

A 
Hypersensitivity= excessive antibody production in response to an innocuous stimulus 
Autoimmunity= pathological immune response against self-antigens
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54
Q

What may remain visible locally after clinical resolution of the trauma regarding a bruise?

A

Haemosiderin-laden macrophages

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55
Q

Describe Urticaria

A

Acute, variable pruritic, oedematous skin lesions- Type 1 hypersensitivity reaction
Caused by mediators of basophils and mast cells
Drugs, foods and food additives are frequent causes
Distribution= variable, from localised to widespread
Discrete, well-circumscribed, round erythematous and oedematous plaques
Histology: variable, non-specific. Subtle or prominent dermal oedema of the superficial dermis
Angioedema: larger, less demarcated swelling of deep dermis and subcutis

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56
Q

Urticaria is caused by mediators of what?

A

Basophils and mast cells

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57
Q

Describe atopic dermatitis

A

Increased production of IgE against ‘innocuous’ antigens
Prominent Th2 reactivity -> IgE hypersecretion and deficient cell-mediated immune response -> higher susceptibility to local infections
Very pruritic
Typically on ventral sparsely-haired skin
Excoriations, papules, pustules, hyper-pigmentation and lichenification are secondary to trauma induced by pruritis
Histology: perivascular to interstitial lymphoplasmacytic dermatitis with oedema, eosinophils, macrophages and variable degree of epidermal hyperplasia

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58
Q

Describe food allergy dermatitis

A

Exaggerated immune response against food allergens
Type 1 hypersensitivity
GI tract and skin
Similar to atopic dermatitis
Allergens are encountered in GI tract, and sensitised lymphocytes secondarily reach the skin
Non-seasonal severe pruritus, poorly responsive to corticosteroid treatment

59
Q

Describe insect hypersensitivity

A

Antigens from insect saliva, venom, whole body or faeces
Type I and IV hypersensitivity reactions
Seasonal and pruritic
Flea-bite hypersensitivity= dogs and cats (FAD)
Culicoides hypersensitivity= horses (sweet itch)
Sparsely-haired body regions (lumbosacral-fleas)
Gross lesuion appearance: pruritic crusted papule -> hyperkeratosis, lichenification, seborrhea, excoriation
Histology: eosinophil-dominated dermal perivascular to diffuse dermatitis with lymphocytes

60
Q

Describe skin autoimmunity

A

Pathological immune response against self-antigens -> production of autoantibodies
Uncommon
Several pathological theories:
-Drug can link with endogenous epidermal molecules -> immunogenic
-Infectious agents share sequence homology with some endogenous epitopes

61
Q

Describe Pemphigus foliaceus

A

Autoantibodies against desmoglein 1 (cadherin family= calcium-dependent adhesion molecules; cell adhesion)
Lesions are restricted to skin (no mucosa)
Periocular and nasal skin -> ears, neck, ventral abdomen
Erythematous maculae -> pustules -> erosion and crusts
Histology: acantholytic subcorneal or intragranular pustular dermatitis

62
Q

Describe Pemphigus vulgaris

A

Most severe and rare form
Autoantibodies against desmoglein 3, present on mucous membrane and mucocutaneous junctions
Lesion starts in mouth
Gross lesion appearance: fragile vesicle and bullae -> after rupture, erosion/ulcers
Histology: spongiosis and vacuolation of the suprabasilar layer -> vesicles and bullae above the basal layer. Mild superficial perivascular to interstitial dermatitis (inc. eosinophils)

63
Q

Describe Bullous Pemphigoid

A

Autoantibodies against bullous pemphigoid antigen 1 (BPAG1) and 2 (BPAG2, only one recognised in animals)
Starts at oral cavity and mucocutaneous junctions -> face, groin, axilla,
Vesiculobullous, ulcerative and crusted lesions
Histology: subepidermal vesicles, bullae and ulcers containing neutrophils, eosinophils, other leukocytes. Mild mixed perivascular inflammation

64
Q

What are the 2 forms of lupus eythematosus?

A

Systemic lupus eythematosus (SLE). Involvement of multiple organs with skin lesions in 1/3 affected animals
Discoid lupus eythematosus (DLE). Localised cutaneous form

65
Q

Describe systemic lupus erythematosus

A

Immunoregulatory imbalance -> B cell hyperactivity
Autoantibodies against numerous antigens, mainly antinuclear antibodies against double-stranded DNA, RNA and histones
Main skin tissue damage is provoked by antigen-antibody cpmplexes (type III hypersensitivity)
Skin around eyes, mouth, nostrils, genitalia, perineal skin
Appearance varies from ulcerative to scaling and alopecia
Histology: lichenoid interface dermatitis. Apoptotic keratinocytes, pigmentary incontinence, hyperkeratosis, epidermal hyperplasia

66
Q

Describe discoid lupus erythematosus

A

Localised form, most common in dogs
‘Photosensitive nasal dermatitis’
Nasal planum only
Erythema, depigmentation, scaling, crusting, alopecia, ulcers
Histology: similar to SLE, but more epidermal hyperplasia, denser interface infiltrate dominated by lymphocytes
S. basale

67
Q

What is satellitosis?

A

The abnormal clustering of one cell type around each other

68
Q

Describe erythema multiforma

A

Uncommon, occurs with underlying conditions (eg drug therapy)
Type III and IV hypersensitivity reactions
Deposition of immune complexes in vasculature and basal membrane
Two forms:
-EM minor -> symmetrical bilateral erythematous papules and macules. Classical ‘target’ lesions
-EM major -> widespread mucosal lesions, extensive necrotising and vesiculobullous skin lesions and systemic illness
Histology: characteristic interface dermatitis with necrotic keratinocytes and satellitosis. Epidermal necrosis

69
Q

Describe alopecia areata

A

Focal, multifocal or generalised asymptomatic inflammatory alopecia
Usually skin appears hyperpigmentated, hairs are short or fragmented (dystrophic)
Often spontaneously regresses and new hairs are white (leukotrichia)
Inflammation is restricted to hair bulb
Histology: peribulbar lymphocytic folliculitis -> pigmentary incontinence -> chronic lesions: telogen and atrophic follicles

70
Q

What does lack of Vitamin A cause in skin?

A

Squamous epithelial hyperkeratosis (follicular keratosis)

71
Q

What does lack of Vitamin E cause in skin?

A

Panniculitis due to steatonecrosis (lack of antioxidant protection)

72
Q

What does lack of Vitamin B cause in skin?

A

Dry seborrhea with alopecia

73
Q

Describe how a zinc deficiency affects skin

A

Important co-factor for many enzymes, inc those relates to DNA function
Pigs
D= symmetrical and bilateral on distal legs and around eyes, ears, tail
A= erythematous maculae -> papule covered in dry thick crusts
Histology: acanthosis and epithelial hyperplasia with para-keratotic hyperkeratosis, with prominent basal cell mitotic activity

74
Q

Describe superficial necrolytic dermatitis

A

‘Red, white and blue’ epidermal disease: severe parakeratotic hyerkeratosis (red), spongiosis and oedematous spinous layer (white) and basal layer hyperplasia (blue)
Highly associated with glucagon-secreting pancreatic tumours and end-stage liver disease
D= bilateral and symmetrical on lips, periocular skin, pinna and distal extremities
A= areas of erythema, erosion, ulcers, crusts

75
Q

What causes Cushing’s disease?

A

Hyperadrenocorticism (pituitary gland tumour, adrenal tumour or iatrogenic administration)

76
Q

Describe Cushing’s disease

A

Hyperadrenocorticism (pituitary tumour, adrenal tumour or iatrogenic administration)
No pruritis
Calcinosis cutis due to corticosteroid treatment (calcium deposits in skin)
A & D: bilateral and symmetrical hypotrichosis (sparse hair) and alopecia of trunk, abdomen. Skin is diffusely thinned and less elastic. Hyperpigmentation, comedones (blackheads), calcinosis cutis
Histology: diffuse cutaneous atrophy with ortho-keratotic hyperkeratosis and follicular keratosis

77
Q

What are the causes of hyper-oestrogenism in female and male dogs?

A

Female: polycystic ovaries, functional ovarian neoplasms

Intact males: oestrogen-secreting tumours (sertoliomas)

78
Q

Describe an eosinophilic plaque

A

Cats
Pruritic lesion associated with hypersensitivity
Haired skin of inguinal, axillary, lateral thigh areas
Diffuse and perivascular eosinophilic dermatitis, with epidermal acanthosis and spongiosis

79
Q

Describe an eosinophilic granuloma

A

Cats
Raised, pink, variable pruritic nodular lesions on both haired skin (linear) and oral mucosa (nodular)
Diffuse eosinophilic inflammation with granulomas centred around degenerated collagen bundles covered with degenerate and degranulating eosinophils (flame figures)

80
Q

What is meant by a ‘flame figure’?

A

Degenerate and degranulating eosinophils

81
Q

Name 3 feline eosinophilic dermatoses

A 
Eosinophilic plaque (legs)
Eosinophilic granuloma (mouth)
Indolent ulcer (lips)
82
Q

Name 3 equine eosinophilic nodular diseases

A

Collagenolytic granuloma
Axillary nodular necrosis
Unilateral papular dermatosis

83
Q

Describe collagenolytic granuloma

A

Horses
Single/ multiple nodular, NON-PAINFUL, NON-PRURITIC lesions
Foci of collagen degeneration surrounded by granulomas, sometimes with macrophage palisading and numerous eosinophils

84
Q

Describe axillary necrosis

A

Horses
Nodular, NON-PAINFUL, NON-PRURITIC lesions on trunk behind axilla (girth galls)
Foci of coagulative necrosis with numerous eosinophils and fewer flame figures (may be eosinophilic vasculitis)

85
Q

Describe unilateral papular dermatosis

A

Horses
Seasonal, uncommon unilateral nodules on lateral trunk
Small foci of folliculocentric coagulative necrosis

86
Q

Tumours of the epidermis are derived from which cells?

A

Keratinocytes

87
Q

Describe an epidermal cyst

A

Single dermal mass, not neoplastic
Filled with lamellar keratin, lined by continuous squamous epithelium
Cause:
-Enormous abnormal distention of follicles
-Traumatic dermal implantation of epidermal fragments (rare)

88
Q

Of epithelial and follicular tumours, which are more often malignant?

A

Epithelial

89
Q

How may a papillomavirus infection facilitate the progression of UV light-induced neoplasia?

A

By inhibition of DNA repair and apoptosis, and by inducing proliferation

90
Q

What are koilocytes?

A

Keratinocytes with eccentric pyknotic nucleus (condensation of chromatin in nucleus) and peripheral clear halo (ballooning degeneration)

91
Q

Describe papilomas

A

Epithelial proliferation induced by host- and site-specific Papillomaviruses
Immune system competence linked to susceptibility and regression
Cutaneous papillomas: one/multiple filiform exophytic and hyperkeratotic projections of epidermis, supported by thin dermal stalks (S.spinosum and granulosum)
Fibropapillomas: plaque-like lesions with predominant dermal proliferation (eg Sarcoids)
Single/multiple, bleed easily ->secondary infections

92
Q

Dscribe squamous cell carcinoma

A

All domestic species
Locally invasive and destructive (rarely metastatic)
UV light directly involved in white/pale animas. Viral papillomas can be predisposing condition
A: singe expansile hyperplastic ulcerated or nodular skin lesions
D: mainly on head
Histo: invasive islands and cords of neoplastic cells within dermis. Anisocytosis, anisokaryosis and mitotic index are high. Keratin pearls. Inflammation and desmoplasia. Neutrophilic pustules due to abnormal keratin formation and necrosis

93
Q

Describe basal cell tumours

A

Older cats and dogs
Tumours arise from S. basale
Classified as basal cell carcinoma when malignancy is present without differentiation towards sebaceous gland or follicular wall epithelium
May have connection with superficial epidermis
Head and neck of cats
May recur locally but no metastasis
Histo: cells resembling basal cells. Cords and sheets with indistinct cell boundaries extend into dermis. Cells with small hyperchromatic nuclei and high mitotic index. Desmoplasia

94
Q

Describe the types of follicular tumours

A

Classified according to segment of origin, as assessed by differentiation pattern observed:

  • Infundibular differentiation with keratohyalin granules in granular layer: Infundibular keratinising acanthoma
  • Clear keratinocytes similar to the isthmic outer root sheath cells: Tricholemmoma
  • Signs of matrical differentiation as seen in hair bulb: Pilomatricoma
  • Characteristic of all 3 segments: Trichoepithelioma
  • Formation of primitive hair germ cells: Trichoblastoma
95
Q

Describe an infundibular keratinising acanthoma

A

Single intradermal 0.5-3cm exophytic mass
Central lumen filled with keratin and central pore
Lined by squamous epithelium, only moderately anaplastic
Surrounded by compressed collagen and moderate inflammation

96
Q

Describe a tricholemmoma

A 
Benign neoplasm originating from the external root sheath of the hair follicle 
Clear keratinocytes (isthmic outer root sheath cells)
Central cells with abundant deep eosinophilic cytoplasm (inferior type)
Central tricholemmomal keratinisation (isthmic type)
97
Q

Describe a pilomatricoma

A

Solitary benign tumour, localised to the lower dermis and subcutis
Derived from follicular matrix cells
Chalky white on cut surface, multiobulated and sometimes pigmented
Central portion abruptly filled with ‘ghost cells’ (pale eosinophilic anucleated cells)
Common mineralisation

98
Q

Describe a trichoepithelioma

A

Multilobulated intradermal mass

Trichogenic differentiation to all 3 segments of the hair follicle

99
Q

What are the 4 histological types of trichoblastoma (formation of primitive hair germ cells)

A

Spindle type
Ribbon type
Granular type
Trabecular type

100
Q

Describe the 3 types of sebaceous gland tumours

A

Most common in dogs
Adenoma: well-differentiated, well-demarcated, preponderance of sebocytes, few basaloid cells and ducts
Epithelioma: preponderance of basaloid cells, few sebocytes and ducts. Intermediate degree of malignancy
Adenocarcinoma: cells with variable degree of sebaceous differentiation
-Irregular lobular formations
-Pleomorphism, high mitotic index -> few sebocytes
-Local infiltration -> regional lymph nodes -> lungs?

101
Q

Describe perianal gland tumours

A

Mae dogs, 8+yrs
Castration causes regression in most cases
Solitary/multiple nodular masses, up to 10cm diameter, can ulcerate
Microscopically consist of chords of large acidophilic polygonal ‘hepatoid’ cells surrounded by reserve cells. Mitoses of reserve cells, ulcerations, necrosis

Hepatoid gland adenoma:

  • Compact well-organised lobules
  • Low pleomorphism
  • Well demarcated

Hepatoid gland carcinoma

  • Disorganised lobular pattern
  • Higher cellular atypica and mitotic index
  • Local invasion
102
Q

Describe sweat gland tumours

A

Middle aged dogs

Adenoma of apocrine glands:

  • Gross: well-circumscribed, grey/tan, solid/cystic
  • Histo: well-circumscribed, non-encapsulated dermal nodule formed by multiple cystic tubules lined by well-polarised cuboidal-columnar epithelium, papillary ingrowths

Carcinoma of apocrine glands:

  • Gross: less circumscribed and ulcerated
  • Histo: poorly differentiated, desmoplasia, anaplasia, invasion, metastasis
103
Q

Why are ceruminous gland tumours more common in cats?

A

Horizontal ear canal

104
Q

Describe ceruminous gland tumours

A

Cats (horizontal ear canal)

Grossly: present as obstructive, ulcerated, nodular or pedunculated masses, the cut surface exhibiting a yellow colour

105
Q

What does vitamin D stand for with respect to describing lesions?

A 
Vascuar
Inflammatory
Trauma and chemicals
Autoimmune
Metabolic and hormonal
Idiopathic
Neoplastic
Developmental and Degenerative
106
Q

Describe a fibroma

A

Single intradermal or SC mass, often raised. On cut section: well-circumscribed, non-encapsulated, white to grey derma nodules
Resemble normal mature fibrocytes in interwoven fascicles with abundant collagen production
Excision is curative

107
Q

Equine sarcoids are which kind of skin tumour?

A

Fibroblastic

108
Q

What are the 3 predisposing factors for equine sarcoids?

A

Genetic predisposition, trauma, virus (bovine papillomavirus 1 and 2)

109
Q

Describe equine sarcoids

A

Unique, locally aggressive fibroblastic skin tumour
3 predisposing factors: trauma, genetic predisposition, virus (bovine papillomavirus 1 and 2)
Don’t metastasise
Recur following surgery
Can be occult (alopecic plaque), nodular or mixed verrucous/fibroblastic (wart-like)
Biphasic tumour: both an epidermal and dermal component (although predominantly connective tissue)
Hist: resemble fibromas/low-grade fibrosarcomas.
Neoplastic cells are haphazardly arranged in streams of spindloid cells. Cells show poorly demarcated cytoplasmic borders, faintly eosinophilic cytoplasm. Moderate pleomorphism

110
Q

Describe fibrosarcoma

A

Occur anywhere in skin and subcutis of older dogs and cats

Variable degree of differentiation, rapid infiltrative growth, often recur after removal, metastasis in

111
Q

Describe post-vaccinal fibrosarcomas

A

Cats only
Locally invasive spindle cell sarcoma occurring at site of previous vaccinations
Difficult to cure
Lymphocytic infiltration and remnants of vaccine-induced panniculitis with multinucleated giant cells scattered at periphery of neoplasia

112
Q

Describe myxoma/myxosarcoma

A

Tumours originating from primitive pleomorphic fibroblasts, characterised by their abundant myxoid matrix rich in muco-polysaccharides (glycoaminoglycans)
Locally aggressive malignant tumours
Loosely arranged stellate or spindle cells separated by mucinous stroma

113
Q

Describe canine haemangiopericytoma

A

Neoplastic entity in dogs aged 8-14yrs
Boxer, Springer Spaniel, German Shepherd
Firm to soft, fluctuant, nodular growth, rarely ulcerates, up to 10cm diameter, slow-growing, may be locally infiltrative but rarely metastasises
Formed from pericytes around capillaries
Histo: ‘whorling’ palisade-like fingerprint pattern, sometimes surrounding small capillaries
FL and HL
Non-encapsulated, well-circumscribed dermal or SC nodule formed by the confluence of dilated blood-filled channels lined by flattened endothelium

114
Q

Describe a lipoma

A

Benign tumours of adipose tissue
Encapsulated by a thin fibrous capsule
Common in dogs: older, obese females, trunk and proximal limbs
Excision is curative

115
Q

Describe a haemangiosarcoma

A

More common in older dogs
Grow rapidly
Skin and soft tissues
Distant metastasis (lungs and liver)
Cutaneous haemangiosarcomas less aggressive than visceral
Only clue for morphological recognition= occasional cleft-like spaces
Pleomorphic and plump hyperchromatic spindle cells, vascular channel formation

116
Q

Describe infiltrative lipomas

A

Rare in dogs; middle-aged females, thorax and limbs
Difficult to remove completely as they dissect along fascial planes and between skeletal muscle bundles
Aggressive excision is recommended, amputation may be necessary

117
Q

IHC anti-CD18 is involved in what?
What are they considered markers of?
Which tumours are they associated with?

A

Adhesion and migration of inflammatory cells through activated blood vessels
Markers of monocytes/macrophages
Liposarcomas

118
Q

What are Langerhans cells?

A

Type of WBCs

119
Q

Histiocytoses usually involve which cell type?

A

Langerhans cells

120
Q

Benign systemic histiocytosis affects which dog breed?

Where are they found?

A

Young Bermese Mountain dogs

Skin and lymph nodes; scrotum, nose, eyelids

121
Q

Mastocytomas (mast cell tumours) affect which dog breeds?

A

Boxer, Boston terrier, Labrador

Older dogs

122
Q

What do mast cell tumours present as?

Which skin layers are they found in?

A

Subcutaneous nodules, occasionally as oedematous swellings

Usually localised to dermis, may extend to subcutis and musculature

123
Q

Which cells are found in mastocytomas?

A 
Mast cells (contain metachromatic granules)
Eosinophils
124
Q

Mastocytomas are what grade of tumour?

A

Grade I

Lower malignancy, longer survival times

125
Q

Briefly describe the 3 grades of cutaneous mast cell tumours

A

Grade I: well-differentiated, uniform cells, no giant cells, obvious cytoplasmic granules, uniform nuclei, low malignancy
Grade II: intermediate differentiation, moderate anisocytosis, few giant cells, visible cytoplasmic granules, anisokaryosis, medium malignancy
Grade III: poor differentiation, marked anisocytosis, frequent giant cells, inconspicuous/absent cytoplasmic granules, anisokaryosis, high malignancy

126
Q

Where are extra-medullary plasma cell tumours found?

A

Head and extremities of older dogs

127
Q

What are the two forms of cutaneous malignant lymphoma?

A 
Epitheliotropic form (involving epithelium)
Nodular, non-epitheliotropic form
128
Q

What is the most common form of cutaneous lymphoma in dogs?

A

Epitheliotropic cutaneous (malignant) lymphoma

129
Q

Epitheliotropic cutaneous (malignant) lymphomas are diagnosed as what?

A

Epitheliotropic T cell lymphoma

130
Q

Of epitheliotropic and non-epitheliotropic (malignant) lymphoma, which is more aggressive?

A

Non-epitheliotropic

131
Q

Non- epitheliotropic cutaneous (malignant) lymphomas are diagnosed as what?

A

Cutaneous B cell lymphoma

132
Q

Melanocytic tumours are common in which kind of dogs?

A

Darkly pigmented breeds eg Kerry Blue

133
Q

Where are melanocytic tumours usually found?

A

Face, trunk and extremities

Also gums, oral mucosa, palate and lips

134
Q

Are oral melanomas usually benign or malignant?

A

Malignant

135
Q

Are cutaneous melanotic tumours in dogs usually benign or malignant?

A

Benign, except if on digits or scrotum

136
Q

What is the best indicator of malignancy when looking at tumours?

A

Mitotic figures

137
Q

Regarding melanomas, are poorly melanotic or very melanotic tumours more malignant?

A

Poorly melanotic/amelanotic

138
Q

Briefly describe malignant melanomas

A

Amelanotic, exhibit greater pleomorphism, giant cells, mitoses
Commonly metastasise to regional lymph nodes and lungs

139
Q

Which types of tumours have the greatest metastatic potential?

A

Mammary gland adenocarcinomas, squamous cell carcinomas, transitional cell carcinomas, pulmonary adenocarcinomas and angiosarcomas

140
Q

What should you do if a cat has multiple carcinomas on their feet and why?

A

Check for a lung tumour, as in cats, pulmonary adenocarcinomas preferentially metastasise to the distal extremities

141
Q

Calcinosis circumscripta (tumoral calcinosis) localises where?

A

Bony prominence

142
Q

Describe the early and chronic lesions of Calcinosis circumscripta

A

Early: fluctuant, chalky white -> dermal lakes of von Kossa positive material surrounded by inflammation and fibrosis
Chronic: lesions are firmer -> more mineralised and fibrotic -> osseous or cartilaginous metaplasia can occur

143
Q

Where are lesions from herpes virus dermatitis primarily seen and in which species?

A

Cats

Nasal planum and haired skin of face

Year 3 (28 decks)

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